- 02 Aug, 2012 10 commits
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Konstantin Khlebnikov authored
commit 34dbc67a upstream. Stable note: Not tracked in Bugzilla. There were reports of shared mapped pages being unfairly reclaimed in comparison to older kernels. This is being addressed over time. The specific workload being addressed here in described in paragraph four and while paragraph five says it did not help performance as such, it made a difference to major page faults. I'm aware of at least one bug for a large vendor that was due to increased major faults. Commit 64574746 ("vmscan: detect mapped file pages used only once") greatly decreases lifetime of single-used mapped file pages. Unfortunately it also decreases life time of all shared mapped file pages. Because after commit bf3f3bc5 ("mm: don't mark_page_accessed in fault path") page-fault handler does not mark page active or even referenced. Thus page_check_references() activates file page only if it was used twice while it stays in inactive list, meanwhile it activates anon pages after first access. Inactive list can be small enough, this way reclaimer can accidentally throw away any widely used page if it wasn't used twice in short period. After this patch page_check_references() also activate file mapped page at first inactive list scan if this page is already used multiple times via several ptes. I found this while trying to fix degragation in rhel6 (~2.6.32) from rhel5 (~2.6.18). There a complete mess with >100 web/mail/spam/ftp containers, they share all their files but there a lot of anonymous pages: ~500mb shared file mapped memory and 15-20Gb non-shared anonymous memory. In this situation major-pagefaults are very costly, because all containers share the same page. In my load kernel created a disproportionate pressure on the file memory, compared with the anonymous, they equaled only if I raise swappiness up to 150 =) These patches actually wasn't helped a lot in my problem, but I saw noticable (10-20 times) reduce in count and average time of major-pagefault in file-mapped areas. Actually both patches are fixes for commit v2.6.33-5448-g64574746, because it was aimed at one scenario (singly used pages), but it breaks the logic in other scenarios (shared and/or executable pages) Signed-off-by:
Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by:
Pekka Enberg <penberg@kernel.org> Acked-by:
Minchan Kim <minchan.kim@gmail.com> Reviewed-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Ben Hutchings <ben@decadent.org.uk>
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Mel Gorman authored
commit 0cee34fd upstream. Stable note: Not tracked on Bugzilla. THP and compaction was found to aggressively reclaim pages and stall systems under different situations that was addressed piecemeal over time. If compaction can proceed for a given zone, shrink_zones() does not reclaim any more pages from it. After commit [e0c23279: vmscan: abort reclaim/compaction if compaction can proceed], do_try_to_free_pages() tries to finish as soon as possible once one zone can compact. This was intended to prevent slabs being shrunk unnecessarily but there are side-effects. One is that a small zone that is ready for compaction will abort reclaim even if the chances of successfully allocating a THP from that zone is small. It also means that reclaim can return too early even though sc->nr_to_reclaim pages were not reclaimed. This partially reverts the commit until it is proven that slabs are really being shrunk unnecessarily but preserves the check to return 1 to avoid OOM if reclaim was aborted prematurely. [aarcange@redhat.com: This patch replaces a revert from Andrea] Signed-off-by:
Mel Gorman <mgorman@suse.de> Reviewed-by:
Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by:
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Mel Gorman authored
commit 7335084d upstream. Stable note: Not tracked in Bugzilla. This patch makes later patches easier to apply but otherwise has little to justify it. The problem it fixes was never observed but the source of the theoretical problem did not exist for very long. During direct reclaim it is possible that reclaim will be aborted so that compaction can be attempted to satisfy a high-order allocation. If this decision is made before any pages are reclaimed, it is possible that 0 is returned to the page allocator potentially triggering an OOM. This has not been observed but it is a possibility so this patch addresses it. Signed-off-by:
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Mel Gorman authored
commit fe4b1b24 upstream. Stable note: Not tracked on Bugzilla. THP and compaction was found to aggressively reclaim pages and stall systems under different situations that was addressed piecemeal over time. This patch addresses a problem where the fix regressed THP allocation success rates. In commit e0887c19 ("vmscan: limit direct reclaim for higher order allocations"), Rik noted that reclaim was too aggressive when THP was enabled. In his initial patch he used the number of free pages to decide if reclaim should abort for compaction. My feedback was that reclaim and compaction should be using the same logic when deciding if reclaim should be aborted. Unfortunately, this had the effect of reducing THP success rates when the workload included something like streaming reads that continually allocated pages. The window during which compaction could run and return a THP was too small. This patch combines Rik's two patches together. compaction_suitable() is still used to decide if reclaim should be aborted to allow compaction is used. However, it will also ensure that there is a reasonable buffer of free pages available. This improves upon the THP allocation success rates but bounds the number of pages that are freed for compaction. Signed-off-by:
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Mel Gorman authored
commit a6bc32b8 upstream. Stable note: Not tracked in Buzilla. This was part of a series that reduced interactivity stalls experienced when THP was enabled. These stalls were particularly noticable when copying data to a USB stick but the experiences for users varied a lot. This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT mode that avoids writing back pages to backing storage. Async compaction maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT. For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is used. This avoids sync compaction stalling for an excessive length of time, particularly when copying files to a USB stick where there might be a large number of dirty pages backed by a filesystem that does not support ->writepages. [aarcange@redhat.com: This patch is heavily based on Andrea's work] [akpm@linux-foundation.org: fix fs/nfs/write.c build] [akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build] Signed-off-by:
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Mel Gorman authored
commit c8244935 upstream. Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging information by reducing LRU list churning had the side-effect of reducing THP allocation success rates. This was part of a series to restore the success rates while preserving the reclaim fix. Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware") noted that compaction does not migrate dirty or writeback pages and that is was meaningless to pick the page and re-add it to the LRU list. This had to be partially reverted because some dirty pages can be migrated by compaction without blocking. This patch updates "mm: compaction: make isolate_lru_page" by skipping over pages that migration has no possibility of migrating to minimise LRU disruption. Signed-off-by:
Minchan Kim <minchan@kernel.org> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by:
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Mel Gorman authored
commit 66199712 upstream. Stable note: Not tracked in Buzilla. This was part of a series that reduced interactivity stalls experienced when THP was enabled. If compaction is deferred, direct reclaim is used to try to free enough pages for the allocation to succeed. For small high-orders, this has a reasonable chance of success. However, if the caller has specified __GFP_NO_KSWAPD to limit the disruption to the system, it makes more sense to fail the allocation rather than stall the caller in direct reclaim. This patch skips direct reclaim if compaction is deferred and the caller specifies __GFP_NO_KSWAPD. Async compaction only considers a subset of pages so it is possible for compaction to be deferred prematurely and not enter direct reclaim even in cases where it should. To compensate for this, this patch also defers compaction only if sync compaction failed. Signed-off-by:
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Mel Gorman authored
commit b969c4ab upstream. Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging information by reducing LRU list churning had the side-effect of reducing THP allocation success rates. This was part of a series to restore the success rates while preserving the reclaim fix. Asynchronous compaction is used when allocating transparent hugepages to avoid blocking for long periods of time. Due to reports of stalling, there was a debate on disabling synchronous compaction but this severely impacted allocation success rates. Part of the reason was that many dirty pages are skipped in asynchronous compaction by the following check; if (PageDirty(page) && !sync && mapping->a_ops->migratepage != migrate_page) rc = -EBUSY; This skips over all mapping aops using buffer_migrate_page() even though it is possible to migrate some of these pages without blocking. This patch updates the ->migratepage callback with a "sync" parameter. It is the responsibility of the callback to fail gracefully if migration would block. Signed-off-by:
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Mel Gorman authored
commit a77ebd33 upstream. Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging information by reducing LRU list churning had the side-effect of reducing THP allocation success rates. This was part of a series to restore the success rates while preserving the reclaim fix. Short summary: There are severe stalls when a USB stick using VFAT is used with THP enabled that are reduced by this series. If you are experiencing this problem, please test and report back and considering I have seen complaints from openSUSE and Fedora users on this as well as a few private mails, I'm guessing it's a widespread issue. This is a new type of USB-related stall because it is due to synchronous compaction writing where as in the past the big problem was dirty pages reaching the end of the LRU and being written by reclaim. Am cc'ing Andrew this time and this series would replace mm-do-not-stall-in-synchronous-compaction-for-thp-allocations.patch. I'm also cc'ing Dave Jones as he might have merged that patch to Fedora for wider testing and ideally it would be reverted and replaced by this series. That said, the later patches could really do with some review. If this series is not the answer then a new direction needs to be discussed because as it is, the stalls are unacceptable as the results in this leader show. For testers that try backporting this to 3.1, it won't work because there is a non-obvious dependency on not writing back pages in direct reclaim so you need those patches too. Changelog since V5 o Rebase to 3.2-rc5 o Tidy up the changelogs a bit Changelog since V4 o Added reviewed-bys, credited Andrea properly for sync-light o Allow dirty pages without mappings to be considered for migration o Bound the number of pages freed for compaction o Isolate PageReclaim pages on their own LRU list This is against 3.2-rc5 and follows on from discussions on "mm: Do not stall in synchronous compaction for THP allocations" and "[RFC PATCH 0/5] Reduce compaction-related stalls". Initially, the proposed patch eliminated stalls due to compaction which sometimes resulted in user-visible interactivity problems on browsers by simply never using sync compaction. The downside was that THP success allocation rates were lower because dirty pages were not being migrated as reported by Andrea. His approach at fixing this was nacked on the grounds that it reverted fixes from Rik merged that reduced the amount of pages reclaimed as it severely impacted his workloads performance. This series attempts to reconcile the requirements of maximising THP usage, without stalling in a user-visible fashion due to compaction or cheating by reclaiming an excessive number of pages. Patch 1 partially reverts commit 39deaf85 to allow migration to isolate dirty pages. This is because migration can move some dirty pages without blocking. Patch 2 notes that the /proc/sys/vm/compact_memory handler is not using synchronous compaction when it should be. This is unrelated to the reported stalls but is worth fixing. Patch 3 checks if we isolated a compound page during lumpy scan and account for it properly. For the most part, this affects tracing so it's unrelated to the stalls but worth fixing. Patch 4 notes that it is possible to abort reclaim early for compaction and return 0 to the page allocator potentially entering the "may oom" path. This has not been observed in practice but the rest of the series potentially makes it easier to happen. Patch 5 adds a sync parameter to the migratepage callback and gives the callback responsibility for migrating the page without blocking if sync==false. For example, fallback_migrate_page will not call writepage if sync==false. This increases the number of pages that can be handled by asynchronous compaction thereby reducing stalls. Patch 6 restores filter-awareness to isolate_lru_page for migration. In practice, it means that pages under writeback and pages without a ->migratepage callback will not be isolated for migration. Patch 7 avoids calling direct reclaim if compaction is deferred but makes sure that compaction is only deferred if sync compaction was used. Patch 8 introduces a sync-light migration mechanism that sync compaction uses. The objective is to allow some stalls but to not call ->writepage which can lead to significant user-visible stalls. Patch 9 notes that while we want to abort reclaim ASAP to allow compation to go ahead that we leave a very small window of opportunity for compaction to run. This patch allows more pages to be freed by reclaim but bounds the number to a reasonable level based on the high watermark on each zone. Patch 10 allows slabs to be shrunk even after compaction_ready() is true for one zone. This is to avoid a problem whereby a single small zone can abort reclaim even though no pages have been reclaimed and no suitably large zone is in a usable state. Patch 11 fixes a problem with the rate of page scanning. As reclaim is rarely stalling on pages under writeback it means that scan rates are very high. This is particularly true for direct reclaim which is not calling writepage. The vmstat figures implied that much of this was busy work with PageReclaim pages marked for immediate reclaim. This patch is a prototype that moves these pages to their own LRU list. This has been tested and other than 2 USB keys getting trashed, nothing horrible fell out. That said, I am a bit unhappy with the rescue logic in patch 11 but did not find a better way around it. It does significantly reduce scan rates and System CPU time indicating it is the right direction to take. What is of critical importance is that stalls due to compaction are massively reduced even though sync compaction was still allowed. Testing from people complaining about stalls copying to USBs with THP enabled are particularly welcome. The following tests all involve THP usage and USB keys in some way. Each test follows this type of pattern 1. Read from some fast fast storage, be it raw device or file. Each time the copy finishes, start again until the test ends 2. Write a large file to a filesystem on a USB stick. Each time the copy finishes, start again until the test ends 3. When memory is low, start an alloc process that creates a mapping the size of physical memory to stress THP allocation. This is the "real" part of the test and the part that is meant to trigger stalls when THP is enabled. Copying continues in the background. 4. Record the CPU usage and time to execute of the alloc process 5. Record the number of THP allocs and fallbacks as well as the number of THP pages in use a the end of the test just before alloc exited 6. Run the test 5 times to get an idea of variability 7. Between each run, sync is run and caches dropped and the test waits until nr_dirty is a small number to avoid interference or caching between iterations that would skew the figures. The individual tests were then writebackCPDeviceBasevfat Disable THP, read from a raw device (sda), vfat on USB stick writebackCPDeviceBaseext4 Disable THP, read from a raw device (sda), ext4 on USB stick writebackCPDevicevfat THP enabled, read from a raw device (sda), vfat on USB stick writebackCPDeviceext4 THP enabled, read from a raw device (sda), ext4 on USB stick writebackCPFilevfat THP enabled, read from a file on fast storage and USB, both vfat writebackCPFileext4 THP enabled, read from a file on fast storage and USB, both ext4 The kernels tested were 3.1 3.1 vanilla 3.2-rc5 freemore Patches 1-10 immediate Patches 1-11 andrea The 8 patches Andrea posted as a basis of comparison The results are very long unfortunately. I'll start with the case where we are not using THP at all writebackCPDeviceBasevfat 3.1.0-vanilla rc5-vanilla freemore-v6r1 isolate-v6r1 andrea-v2r1 System Time 1.28 ( 0.00%) 54.49 (-4143.46%) 48.63 (-3687.69%) 4.69 ( -265.11%) 51.88 (-3940.81%) +/- 0.06 ( 0.00%) 2.45 (-4305.55%) 4.75 (-8430.57%) 7.46 (-13282.76%) 4.76 (-8440.70%) User Time 0.09 ( 0.00%) 0.05 ( 40.91%) 0.06 ( 29.55%) 0.07 ( 15.91%) 0.06 ( 27.27%) +/- 0.02 ( 0.00%) 0.01 ( 45.39%) 0.02 ( 25.07%) 0.00 ( 77.06%) 0.01 ( 52.24%) Elapsed Time 110.27 ( 0.00%) 56.38 ( 48.87%) 49.95 ( 54.70%) 11.77 ( 89.33%) 53.43 ( 51.54%) +/- 7.33 ( 0.00%) 3.77 ( 48.61%) 4.94 ( 32.63%) 6.71 ( 8.50%) 4.76 ( 35.03%) THP Active 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) +/- 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Fault Alloc 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) +/- 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) Fault Fallback 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) +/- 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) The THP figures are obviously all 0 because THP was enabled. The main thing to watch is the elapsed times and how they compare to times when THP is enabled later. It's also important to note that elapsed time is improved by this series as System CPu time is much reduced. writebackCPDevicevfat 3.1.0-vanilla rc5-vanilla freemore-v6r1 isolate-v6r1 andrea-v2r1 System Time 1.22 ( 0.00%) 13.89 (-1040.72%) 46.40 (-3709.20%) 4.44 ( -264.37%) 47.37 (-3789.33%) +/- 0.06 ( 0.00%) 22.82 (-37635.56%) 3.84 (-6249.44%) 6.48 (-10618.92%) 6.60 (-10818.53%) User Time 0.06 ( 0.00%) 0.06 ( -6.90%) 0.05 ( 17.24%) 0.05 ( 13.79%) 0.04 ( 31.03%) +/- 0.01 ( 0.00%) 0.01 ( 33.33%) 0.01 ( 33.33%) 0.01 ( 39.14%) 0.01 ( 25.46%) Elapsed Time 10445.54 ( 0.00%) 2249.92 ( 78.46%) 70.06 ( 99.33%) 16.59 ( 99.84%) 472.43 ( 95.48%) +/- 643.98 ( 0.00%) 811.62 ( -26.03%) 10.02 ( 98.44%) 7.03 ( 98.91%) 59.99 ( 90.68%) THP Active 15.60 ( 0.00%) 35.20 ( 225.64%) 65.00 ( 416.67%) 70.80 ( 453.85%) 62.20 ( 398.72%) +/- 18.48 ( 0.00%) 51.29 ( 277.59%) 15.99 ( 86.52%) 37.91 ( 205.18%) 22.02 ( 119.18%) Fault Alloc 121.80 ( 0.00%) 76.60 ( 62.89%) 155.40 ( 127.59%) 181.20 ( 148.77%) 286.60 ( 235.30%) +/- 73.51 ( 0.00%) 61.11 ( 83.12%) 34.89 ( 47.46%) 31.88 ( 43.36%) 68.13 ( 92.68%) Fault Fallback 881.20 ( 0.00%) 926.60 ( -5.15%) 847.60 ( 3.81%) 822.00 ( 6.72%) 716.60 ( 18.68%) +/- 73.51 ( 0.00%) 61.26 ( 16.67%) 34.89 ( 52.54%) 31.65 ( 56.94%) 67.75 ( 7.84%) MMTests Statistics: duration User/Sys Time Running Test (seconds) 3540.88 1945.37 716.04 64.97 1937.03 Total Elapsed Time (seconds) 52417.33 11425.90 501.02 230.95 2520.28 The first thing to note is the "Elapsed Time" for the vanilla kernels of 2249 seconds versus 56 with THP disabled which might explain the reports of USB stalls with THP enabled. Applying the patches brings performance in line with THP-disabled performance while isolating pages for immediate reclaim from the LRU cuts down System CPU time. The "Fault Alloc" success rate figures are also improved. The vanilla kernel only managed to allocate 76.6 pages on average over the course of 5 iterations where as applying the series allocated 181.20 on average albeit it is well within variance. It's worth noting that applies the series at least descreases the amount of variance which implies an improvement. Andrea's series had a higher success rate for THP allocations but at a severe cost to elapsed time which is still better than vanilla but still much worse than disabling THP altogether. One can bring my series close to Andrea's by removing this check /* * If compaction is deferred for high-order allocations, it is because * sync compaction recently failed. In this is the case and the caller * has requested the system not be heavily disrupted, fail the * allocation now instead of entering direct reclaim */ if (deferred_compaction && (gfp_mask & __GFP_NO_KSWAPD)) goto nopage; I didn't include a patch that removed the above check because hurting overall performance to improve the THP figure is not what the average user wants. It's something to consider though if someone really wants to maximise THP usage no matter what it does to the workload initially. This is summary of vmstat figures from the same test. 3.1.0-vanilla rc5-vanilla freemore-v6r1 isolate-v6r1 andrea-v2r1 Page Ins 3257266139 1111844061 17263623 10901575 161423219 Page Outs 81054922 30364312 3626530 3657687 8753730 Swap Ins 3294 2851 6560 4964 4592 Swap Outs 390073 528094 620197 790912 698285 Direct pages scanned 1077581700 3024951463 1764930052 115140570 5901188831 Kswapd pages scanned 34826043 7112868 2131265 1686942 1893966 Kswapd pages reclaimed 28950067 4911036 1246044 966475 1497726 Direct pages reclaimed 805148398 280167837 3623473 2215044 40809360 Kswapd efficiency 83% 69% 58% 57% 79% Kswapd velocity 664.399 622.521 4253.852 7304.360 751.490 Direct efficiency 74% 9% 0% 1% 0% Direct velocity 20557.737 264745.137 3522673.849 498551.938 2341481.435 Percentage direct scans 96% 99% 99% 98% 99% Page writes by reclaim 722646 529174 620319 791018 699198 Page writes file 332573 1080 122 106 913 Page writes anon 390073 528094 620197 790912 698285 Page reclaim immediate 0 2552514720 1635858848 111281140 5478375032 Page rescued immediate 0 0 0 87848 0 Slabs scanned 23552 23552 9216 8192 9216 Direct inode steals 231 0 0 0 0 Kswapd inode steals 0 0 0 0 0 Kswapd skipped wait 28076 786 0 61 6 THP fault alloc 609 383 753 906 1433 THP collapse alloc 12 6 0 0 6 THP splits 536 211 456 593 1136 THP fault fallback 4406 4633 4263 4110 3583 THP collapse fail 120 127 0 0 4 Compaction stalls 1810 728 623 779 3200 Compaction success 196 53 60 80 123 Compaction failures 1614 675 563 699 3077 Compaction pages moved 193158 53545 243185 333457 226688 Compaction move failure 9952 9396 16424 23676 45070 The main things to look at are 1. Page In/out figures are much reduced by the series. 2. Direct page scanning is incredibly high (264745.137 pages scanned per second on the vanilla kernel) but isolating PageReclaim pages on their own list reduces the number of pages scanned significantly. 3. The fact that "Page rescued immediate" is a positive number implies that we sometimes race removing pages from the LRU_IMMEDIATE list that need to be put back on a normal LRU but it happens only for 0.07% of the pages marked for immediate reclaim. writebackCPDeviceext4 3.1.0-vanilla rc5-vanilla freemore-v6r1 isolate-v6r1 andrea-v2r1 System Time 1.51 ( 0.00%) 1.77 ( -17.66%) 1.46 ( 2.92%) 1.15 ( 23.77%) 1.89 ( -25.63%) +/- 0.27 ( 0.00%) 0.67 ( -148.52%) 0.33 ( -22.76%) 0.30 ( -11.15%) 0.19 ( 30.16%) User Time 0.03 ( 0.00%) 0.04 ( -37.50%) 0.05 ( -62.50%) 0.07 ( -112.50%) 0.04 ( -18.75%) +/- 0.01 ( 0.00%) 0.02 ( -146.64%) 0.02 ( -97.91%) 0.02 ( -75.59%) 0.02 ( -63.30%) Elapsed Time 124.93 ( 0.00%) 114.49 ( 8.36%) 96.77 ( 22.55%) 27.48 ( 78.00%) 205.70 ( -64.65%) +/- 20.20 ( 0.00%) 74.39 ( -268.34%) 59.88 ( -196.48%) 7.72 ( 61.79%) 25.03 ( -23.95%) THP Active 161.80 ( 0.00%) 83.60 ( 51.67%) 141.20 ( 87.27%) 84.60 ( 52.29%) 82.60 ( 51.05%) +/- 71.95 ( 0.00%) 43.80 ( 60.88%) 26.91 ( 37.40%) 59.02 ( 82.03%) 52.13 ( 72.45%) Fault Alloc 471.40 ( 0.00%) 228.60 ( 48.49%) 282.20 ( 59.86%) 225.20 ( 47.77%) 388.40 ( 82.39%) +/- 88.07 ( 0.00%) 87.42 ( 99.26%) 73.79 ( 83.78%) 109.62 ( 124.47%) 82.62 ( 93.81%) Fault Fallback 531.60 ( 0.00%) 774.60 ( -45.71%) 720.80 ( -35.59%) 777.80 ( -46.31%) 614.80 ( -15.65%) +/- 88.07 ( 0.00%) 87.26 ( 0.92%) 73.79 ( 16.22%) 109.62 ( -24.47%) 82.29 ( 6.56%) MMTests Statistics: duration User/Sys Time Running Test (seconds) 50.22 33.76 30.65 24.14 128.45 Total Elapsed Time (seconds) 1113.73 1132.19 1029.45 759.49 1707.26 Similar test but the USB stick is using ext4 instead of vfat. As ext4 does not use writepage for migration, the large stalls due to compaction when THP is enabled are not observed. Still, isolating PageReclaim pages on their own list helped completion time largely by reducing the number of pages scanned by direct reclaim although time spend in congestion_wait could also be a factor. Again, Andrea's series had far higher success rates for THP allocation at the cost of elapsed time. I didn't look too closely but a quick look at the vmstat figures tells me kswapd reclaimed 8 times more pages than the patch series and direct reclaim reclaimed roughly three times as many pages. It follows that if memory is aggressively reclaimed, there will be more available for THP. writebackCPFilevfat 3.1.0-vanilla rc5-vanilla freemore-v6r1 isolate-v6r1 andrea-v2r1 System Time 1.76 ( 0.00%) 29.10 (-1555.52%) 46.01 (-2517.18%) 4.79 ( -172.35%) 54.89 (-3022.53%) +/- 0.14 ( 0.00%) 25.61 (-18185.17%) 2.15 (-1434.83%) 6.60 (-4610.03%) 9.75 (-6863.76%) User Time 0.05 ( 0.00%) 0.07 ( -45.83%) 0.05 ( -4.17%) 0.06 ( -29.17%) 0.06 ( -16.67%) +/- 0.02 ( 0.00%) 0.02 ( 20.11%) 0.02 ( -3.14%) 0.01 ( 31.58%) 0.01 ( 47.41%) Elapsed Time 22520.79 ( 0.00%) 1082.85 ( 95.19%) 73.30 ( 99.67%) 32.43 ( 99.86%) 291.84 ( 98.70%) +/- 7277.23 ( 0.00%) 706.29 ( 90.29%) 19.05 ( 99.74%) 17.05 ( 99.77%) 125.55 ( 98.27%) THP Active 83.80 ( 0.00%) 12.80 ( 15.27%) 15.60 ( 18.62%) 13.00 ( 15.51%) 0.80 ( 0.95%) +/- 66.81 ( 0.00%) 20.19 ( 30.22%) 5.92 ( 8.86%) 15.06 ( 22.54%) 1.17 ( 1.75%) Fault Alloc 171.00 ( 0.00%) 67.80 ( 39.65%) 97.40 ( 56.96%) 125.60 ( 73.45%) 133.00 ( 77.78%) +/- 82.91 ( 0.00%) 30.69 ( 37.02%) 53.91 ( 65.02%) 55.05 ( 66.40%) 21.19 ( 25.56%) Fault Fallback 832.00 ( 0.00%) 935.20 ( -12.40%) 906.00 ( -8.89%) 877.40 ( -5.46%) 870.20 ( -4.59%) +/- 82.91 ( 0.00%) 30.69 ( 62.98%) 54.01 ( 34.86%) 55.05 ( 33.60%) 20.91 ( 74.78%) MMTests Statistics: duration User/Sys Time Running Test (seconds) 7229.81 928.42 704.52 80.68 1330.76 Total Elapsed Time (seconds) 112849.04 5618.69 571.11 360.54 1664.28 In this case, the test is reading/writing only from filesystems but as it's vfat, it's slow due to calling writepage during compaction. Little to observe really - the time to complete the test goes way down with the series applied and THP allocation success rates go up in comparison to 3.2-rc5. The success rates are lower than 3.1.0 but the elapsed time for that kernel is abysmal so it is not really a sensible comparison. As before, Andrea's series allocates more THPs at the cost of overall performance. writebackCPFileext4 3.1.0-vanilla rc5-vanilla freemore-v6r1 isolate-v6r1 andrea-v2r1 System Time 1.51 ( 0.00%) 1.77 ( -17.66%) 1.46 ( 2.92%) 1.15 ( 23.77%) 1.89 ( -25.63%) +/- 0.27 ( 0.00%) 0.67 ( -148.52%) 0.33 ( -22.76%) 0.30 ( -11.15%) 0.19 ( 30.16%) User Time 0.03 ( 0.00%) 0.04 ( -37.50%) 0.05 ( -62.50%) 0.07 ( -112.50%) 0.04 ( -18.75%) +/- 0.01 ( 0.00%) 0.02 ( -146.64%) 0.02 ( -97.91%) 0.02 ( -75.59%) 0.02 ( -63.30%) Elapsed Time 124.93 ( 0.00%) 114.49 ( 8.36%) 96.77 ( 22.55%) 27.48 ( 78.00%) 205.70 ( -64.65%) +/- 20.20 ( 0.00%) 74.39 ( -268.34%) 59.88 ( -196.48%) 7.72 ( 61.79%) 25.03 ( -23.95%) THP Active 161.80 ( 0.00%) 83.60 ( 51.67%) 141.20 ( 87.27%) 84.60 ( 52.29%) 82.60 ( 51.05%) +/- 71.95 ( 0.00%) 43.80 ( 60.88%) 26.91 ( 37.40%) 59.02 ( 82.03%) 52.13 ( 72.45%) Fault Alloc 471.40 ( 0.00%) 228.60 ( 48.49%) 282.20 ( 59.86%) 225.20 ( 47.77%) 388.40 ( 82.39%) +/- 88.07 ( 0.00%) 87.42 ( 99.26%) 73.79 ( 83.78%) 109.62 ( 124.47%) 82.62 ( 93.81%) Fault Fallback 531.60 ( 0.00%) 774.60 ( -45.71%) 720.80 ( -35.59%) 777.80 ( -46.31%) 614.80 ( -15.65%) +/- 88.07 ( 0.00%) 87.26 ( 0.92%) 73.79 ( 16.22%) 109.62 ( -24.47%) 82.29 ( 6.56%) MMTests Statistics: duration User/Sys Time Running Test (seconds) 50.22 33.76 30.65 24.14 128.45 Total Elapsed Time (seconds) 1113.73 1132.19 1029.45 759.49 1707.26 Same type of story - elapsed times go down. In this case, allocation success rates are roughtly the same. As before, Andrea's has higher success rates but takes a lot longer. Overall the series does reduce latencies and while the tests are inherency racy as alloc competes with the cp processes, the variability was included. The THP allocation rates are not as high as they could be but that is because we would have to be more aggressive about reclaim and compaction impacting overall performance. This patch: Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware") noted that compaction does not migrate dirty or writeback pages and that is was meaningless to pick the page and re-add it to the LRU list. What was missed during review is that asynchronous migration moves dirty pages if their ->migratepage callback is migrate_page() because these can be moved without blocking. This potentially impacted hugepage allocation success rates by a factor depending on how many dirty pages are in the system. This patch partially reverts 39deaf85 to allow migration to isolate dirty pages again. This increases how much compaction disrupts the LRU but that is addressed later in the series. Signed-off-by:
Andrea Arcangeli <aarcange@redhat.com> Reviewed-by:
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Mel Gorman authored
commit 938929f1 upstream. Stable note: Fixes https://bugzilla.novell.com/show_bug.cgi?id=726210 . Large machines with 1TB or more of RAM take a long time to boot without this patch and may spew out soft lockup warnings. When min_free_kbytes is updated, some pageblocks are marked MIGRATE_RESERVE. Ordinarily, this work is unnoticable as it happens early in boot but on large machines with 1TB of memory, this has been reported to delay boot times, probably due to the NUMA distances involved. The bulk of the work is due to calling calling pageblock_is_reserved() an unnecessary amount of times and accessing far more struct page metadata than is necessary. This patch significantly reduces the amount of work done by setup_zone_migrate_reserve() improving boot times on 1TB machines. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
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- 25 Jul, 2012 30 commits
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Ben Hutchings authored
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Ryan Bourgeois authored
commit b2e6ad7d upstream. Add support for the 15'' MacBook Pro Retina. The keyboard is the same as recent models. The patch needs to be synchronized with the bcm5974 patch for the trackpad - as usual. Patch originally written by clipcarl (forums.opensuse.org). [rydberg@euromail.se: Amended mouse ignore lines] Signed-off-by:
Ryan Bourgeois <bluedragonx@gmail.com> Signed-off-by:
Henrik Rydberg <rydberg@euromail.se> Acked-by:
Jiri Kosina <jkosina@suse.cz> Signed-off-by:
Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by:
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Yuri Khan authored
commit e76b8ee2 upstream. I couldn't find the vendor ID in any of the online databases, but this mat has a Pump It Up logo on the top side of the controller compartment, and a disclaimer stating that Andamiro will not be liable on the bottom. Signed-off-by:
Yuri Khan <yurivkhan@gmail.com> Signed-off-by:
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Ilia Katsnelson authored
commit cc71a7e8 upstream. Signed-off-by:
Ilia Katsnelson <k0009000@gmail.com> Signed-off-by:
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Yuri Khan authored
commit 3ffb62cb upstream. The device should be handled by xpad driver instead of generic HID driver. Signed-off-by:
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Henrik Rydberg authored
commit 3dde22a9 upstream. Add support for the 15'' MacBook Pro Retina model (MacBookPro10,1). Patch originally written by clipcarl (forums.opensuse.org). Signed-off-by:
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Eric W. Biederman authored
commit a64d49c3 upstream. It was recently reported that moving a bonding device between network namespaces causes warnings from /proc. It turns out after the move we were trying to add and to remove the /proc/net/bonding entries from the wrong network namespace. Move the bonding /proc registration code into the NETDEV_REGISTER and NETDEV_UNREGISTER events where the proc registration and unregistration will always happen at the right time. Signed-off-by:
"Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
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Eric W. Biederman authored
commit 96ca7ffe upstream. The bonding debugfs support has been broken in the presence of network namespaces since it has been added. The debugfs support does not handle multiple bonding devices with the same name in different network namespaces. I haven't had any bug reports, and I'm not interested in getting any. Disable the debugfs support when network namespaces are enabled. Signed-off-by:
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Deepak Sikri authored
commit 8e839891 upstream. It was observed that during multiple reboots nfs hangs. The status of receive descriptors shows that all the descriptors were in control of CPU, and none were assigned to DMA. Also the DMA status register confirmed that the Rx buffer is unavailable. This patch adds the fix for the same by adding the memory barriers to ascertain that the all instructions before enabling the Rx or Tx DMA are completed which involves the proper setting of the ownership bit in DMA descriptors. Signed-off-by:
Deepak Sikri <deepak.sikri@st.com> Signed-off-by:
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Davide Gerhard authored
commit 6de0298e upstream. This adds support for the iPad to the ipheth driver. (product id = 0x129a) Signed-off-by:
Davide Gerhard <rainbow@irh.it> Signed-off-by:
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Rafael J. Wysocki authored
commit dbe9a2ed upstream. The comparison between the system sleep state being entered and the lowest system sleep state the given device may wake up from in acpi_pm_device_sleep_state() is reversed, because the specification (ACPI 5.0) says that for wakeup to work: "The sleeping state being entered must be less than or equal to the power state declared in element 1 of the _PRW object." In other words, the state returned by _PRW is the deepest (lowest-power) system sleep state the device is capable of waking up the system from. Moreover, acpi_pm_device_sleep_state() also should check if the wakeup capability is supported through ACPI, because in principle it may be done via native PCIe PME, for example, in which case _SxW should not be evaluated. Signed-off-by:
Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by:
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Tyler Hicks authored
commit 9fe79d76 upstream. If the first attempt at opening the lower file read/write fails, eCryptfs will retry using a privileged kthread. However, the privileged retry should not happen if the lower file's inode is read-only because a read/write open will still be unsuccessful. The check for determining if the open should be retried was intended to be based on the access mode of the lower file's open flags being O_RDONLY, but the check was incorrectly performed. This would cause the open to be retried by the privileged kthread, resulting in a second failed open of the lower file. This patch corrects the check to determine if the open request should be handled by the privileged kthread. Signed-off-by:
Tyler Hicks <tyhicks@canonical.com> Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Acked-by:
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Tyler Hicks authored
commit 60d65f1f upstream. Don't grab the daemon mutex while holding the message context mutex. Addresses this lockdep warning: ecryptfsd/2141 is trying to acquire lock: (&ecryptfs_msg_ctx_arr[i].mux){+.+.+.}, at: [<ffffffffa029c213>] ecryptfs_miscdev_read+0x143/0x470 [ecryptfs] but task is already holding lock: (&(*daemon)->mux){+.+...}, at: [<ffffffffa029c2ec>] ecryptfs_miscdev_read+0x21c/0x470 [ecryptfs] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&(*daemon)->mux){+.+...}: [<ffffffff810a3b8d>] lock_acquire+0x9d/0x220 [<ffffffff8151c6da>] __mutex_lock_common+0x5a/0x4b0 [<ffffffff8151cc64>] mutex_lock_nested+0x44/0x50 [<ffffffffa029c5d7>] ecryptfs_send_miscdev+0x97/0x120 [ecryptfs] [<ffffffffa029b744>] ecryptfs_send_message+0x134/0x1e0 [ecryptfs] [<ffffffffa029a24e>] ecryptfs_generate_key_packet_set+0x2fe/0xa80 [ecryptfs] [<ffffffffa02960f8>] ecryptfs_write_metadata+0x108/0x250 [ecryptfs] [<ffffffffa0290f80>] ecryptfs_create+0x130/0x250 [ecryptfs] [<ffffffff811963a4>] vfs_create+0xb4/0x120 [<ffffffff81197865>] do_last+0x8c5/0xa10 [<ffffffff811998f9>] path_openat+0xd9/0x460 [<ffffffff81199da2>] do_filp_open+0x42/0xa0 [<ffffffff81187998>] do_sys_open+0xf8/0x1d0 [<ffffffff81187a91>] sys_open+0x21/0x30 [<ffffffff81527d69>] system_call_fastpath+0x16/0x1b -> #0 (&ecryptfs_msg_ctx_arr[i].mux){+.+.+.}: [<ffffffff810a3418>] __lock_acquire+0x1bf8/0x1c50 [<ffffffff810a3b8d>] lock_acquire+0x9d/0x220 [<ffffffff8151c6da>] __mutex_lock_common+0x5a/0x4b0 [<ffffffff8151cc64>] mutex_lock_nested+0x44/0x50 [<ffffffffa029c213>] ecryptfs_miscdev_read+0x143/0x470 [ecryptfs] [<ffffffff811887d3>] vfs_read+0xb3/0x180 [<ffffffff811888ed>] sys_read+0x4d/0x90 [<ffffffff81527d69>] system_call_fastpath+0x16/0x1b Signed-off-by:
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Tyler Hicks authored
commit 8dc67805 upstream. File operations on /dev/ecryptfs would BUG() when the operations were performed by processes other than the process that originally opened the file. This could happen with open files inherited after fork() or file descriptors passed through IPC mechanisms. Rather than calling BUG(), an error code can be safely returned in most situations. In ecryptfs_miscdev_release(), eCryptfs still needs to handle the release even if the last file reference is being held by a process that didn't originally open the file. ecryptfs_find_daemon_by_euid() will not be successful, so a pointer to the daemon is stored in the file's private_data. The private_data pointer is initialized when the miscdev file is opened and only used when the file is released. https://launchpad.net/bugs/994247Signed-off-by:
Sasha Levin <levinsasha928@gmail.com> Tested-by:
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Pavel Vasilyev authored
commit 9f132652 upstream. Current code is ignoring the last character of "enable" and "disable" in comparisons. https://bugzilla.kernel.org/show_bug.cgi?id=33732Signed-off-by:
Len Brown <len.brown@intel.com> Signed-off-by:
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Zhang Rui authored
commit 76eb9a30 upstream. Dell Precision M6600 is known to require PCI reboot, so add it to the reboot blacklist in pci_reboot_dmi_table[]. https://bugzilla.kernel.org/show_bug.cgi?id=42749 cc: x86@kernel.org Signed-off-by:
Zhang Rui <rui.zhang@intel.com> Signed-off-by:
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Feng Tang authored
commit b939c2ac upstream. commit f6b54f08 upstream. This is the 2nd part of fix for kernel bugzilla 40002: "IRQ 0 assigned to VGA" https://bugzilla.kernel.org/show_bug.cgi?id=40002 The root cause is the buggy FW, whose ACPI tables assign the GSI 16 to 2 irqs 0 and 16(VGA), and the VGA is the right owner of GSI 16. So add a quirk to ignore the irq0 overriding GSI 16 for the FUJITSU SIEMENS AMILO PRO V2030 platform will solve this issue. Reported-and-tested-by:
Szymon Kowalczyk <fazerxlo@o2.pl> Signed-off-by:
Feng Tang <feng.tang@intel.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by:
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Feng Tang authored
commit 5752cdb8 upstream. commit 7f68b4c2 upstream. Current WARN msg is only for the ati_ixp4x0 board, while this function is used by mulitple platforms. So this one board specific warning is not appropriate any more. Signed-off-by:
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Feng Tang authored
commit ae10ccdc upstream. Currently when acpi_skip_timer_override is set, it only cover the (source_irq == 0 && global_irq == 2) cases. While there is also platform which need use this option and its global_irq is not 2. This patch will extend acpi_skip_timer_override to cover all timer overriding cases as long as the source irq is 0. This is the first part of a fix to kernel bug bugzilla 40002: "IRQ 0 assigned to VGA" https://bugzilla.kernel.org/show_bug.cgi?id=40002Reported-and-tested-by:
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Eric Dumazet authored
commit 62b1a8ab upstream. Orphaning skb in dev_hard_start_xmit() makes bonding behavior unfriendly for applications sending big UDP bursts : Once packets pass the bonding device and come to real device, they might hit a full qdisc and be dropped. Without orphaning, the sender is automatically throttled because sk->sk_wmemalloc reaches sk->sk_sndbuf (assuming sk_sndbuf is not too big) We could try to defer the orphaning adding another test in dev_hard_start_xmit(), but all this seems of little gain, now that BQL tends to make packets more likely to be parked in Qdisc queues instead of NIC TX ring, in cases where performance matters. Reverts commits : fc6055a5 net: Introduce skb_orphan_try() 87fd308c net: skb_tx_hash() fix relative to skb_orphan_try() and removes SKBTX_DRV_NEEDS_SK_REF flag Reported-and-bisected-by:
Jean-Michel Hautbois <jhautbois@gmail.com> Signed-off-by:
Eric Dumazet <edumazet@google.com> Tested-by:
Oliver Hartkopp <socketcan@hartkopp.net> Acked-by:
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Eric Dumazet authored
commit bc14786a upstream. There is a off by one error in the minimal number of BD in bnx2x_start_xmit() and bnx2x_tx_int() before stopping/resuming tx queue. A full size GSO packet, with data included in skb->head really needs (MAX_SKB_FRAGS + 4) BDs, because of bnx2x_tx_split() This error triggers if BQL is disabled and heavy TCP transmit traffic occurs. bnx2x_tx_split() definitely can be called, remove a wrong comment. Reported-by:
Tomas Hruby <thruby@google.com> Signed-off-by:
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Eric Dumazet authored
commit d6cb3e41 upstream. bnx2x driver incorrectly sets ip_summed to CHECKSUM_UNNECESSARY on encapsulated segments. TCP stack happily accepts frames with bad checksums, if they are inside a GRE or IPIP encapsulation. Our understanding is that if no IP or L4 csum validation was done by the hardware, we should leave ip_summed as is (CHECKSUM_NONE), since hardware doesn't provide CHECKSUM_COMPLETE support in its cqe. Then, if IP/L4 checksumming was done by the hardware, set CHECKSUM_UNNECESSARY if no error was flagged. Patch based on findings and analysis from Robert Evans Signed-off-by:
Eilon Greenstein <eilong@broadcom.com> Signed-off-by:
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Devendra Naga authored
commit ad1be8d3 upstream. when register_netdev fails, the init'ed NAPIs by netif_napi_add must be deleted with netif_napi_del, and also when driver unloads, it should delete the NAPI before unregistering netdevice using unregister_netdev. Signed-off-by:
Devendra Naga <devendra.aaru@gmail.com> Signed-off-by:
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Nadav Har'El authored
commit d550dda1 upstream. This is a tiny, but important, patch to vhost. Vhost's worker thread only called schedule() when it had no work to do, and it wanted to go to sleep. But if there's always work to do, e.g., the guest is running a network-intensive program like netperf with small message sizes, schedule() was *never* called. This had several negative implications (on non-preemptive kernels): 1. Passing time was not properly accounted to the "vhost" process (ps and top would wrongly show it using zero CPU time). 2. Sometimes error messages about RCU timeouts would be printed, if the core running the vhost thread didn't schedule() for a very long time. 3. Worst of all, a vhost thread would "hog" the core. If several vhost threads need to share the same core, typically one would get most of the CPU time (and its associated guest most of the performance), while the others hardly get any work done. The trivial solution is to add if (need_resched()) schedule(); After doing every piece of work. This will not do the heavy schedule() all the time, just when the timer interrupt decided a reschedule is warranted (so need_resched returns true). Thanks to Abel Gordon for this patch. Signed-off-by:
Nadav Har'El <nyh@il.ibm.com> Signed-off-by:
Michael S. Tsirkin <mst@redhat.com> Signed-off-by:
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Andreas Schwab authored
commit 9f5072d4 upstream. Commit d57af9b2 (taskstats: use real microsecond granularity for CPU times) renamed msecs_to_cputime to usecs_to_cputime, but failed to update all numbers on the way. This causes nonsensical cpu idle/iowait values to be displayed in /proc/stat (the only user of usecs_to_cputime so far). This also renames __cputime_msec_factor to __cputime_usec_factor, adapting its value and using it directly in cputime_to_usecs instead of doing two multiplications. Signed-off-by:
Andreas Schwab <schwab@linux-m68k.org> Acked-by:
Anton Blanchard <anton@samba.org> Signed-off-by:
Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by:
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Thomas Gleixner authored
This is a backport of 3e997130 The leap second rework unearthed another issue of inconsistent data. On timekeeping_resume() the timekeeper data is updated, but nothing calls timekeeping_update(), so now the update code in the timer interrupt sees stale values. This has been the case before those changes, but then the timer interrupt was using stale data as well so this went unnoticed for quite some time. Add the missing update call, so all the data is consistent everywhere. Reported-by:
Martin Steigerwald <Martin@lichtvoll.de> Cc: LKML <linux-kernel@vger.kernel.org> Cc: Linux PM list <linux-pm@vger.kernel.org> Cc: John Stultz <johnstul@us.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
John Stultz <johnstul@us.ibm.com> Signed-off-by:
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John Stultz authored
commit 5baefd6d upstream. The update of the hrtimer base offsets on all cpus cannot be made atomically from the timekeeper.lock held and interrupt disabled region as smp function calls are not allowed there. clock_was_set(), which enforces the update on all cpus, is called either from preemptible process context in case of do_settimeofday() or from the softirq context when the offset modification happened in the timer interrupt itself due to a leap second. In both cases there is a race window for an hrtimer interrupt between dropping timekeeper lock, enabling interrupts and clock_was_set() issuing the updates. Any interrupt which arrives in that window will see the new time but operate on stale offsets. So we need to make sure that an hrtimer interrupt always sees a consistent state of time and offsets. ktime_get_update_offsets() allows us to get the current monotonic time and update the per cpu hrtimer base offsets from hrtimer_interrupt() to capture a consistent state of monotonic time and the offsets. The function replaces the existing ktime_get() calls in hrtimer_interrupt(). The overhead of the new function vs. ktime_get() is minimal as it just adds two store operations. This ensures that any changes to realtime or boottime offsets are noticed and stored into the per-cpu hrtimer base structures, prior to any hrtimer expiration and guarantees that timers are not expired early. Signed-off-by:
Ingo Molnar <mingo@kernel.org> Acked-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by:
Prarit Bhargava <prarit@redhat.com> Link: http://lkml.kernel.org/r/1341960205-56738-8-git-send-email-johnstul@us.ibm.comSigned-off-by:
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Thomas Gleixner authored
This is a backport of f6c06abf To finally fix the infamous leap second issue and other race windows caused by functions which change the offsets between the various time bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a function which atomically gets the current monotonic time and updates the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic overhead. The previous patch which provides ktime_t offsets allows us to make this function almost as cheap as ktime_get() which is going to be replaced in hrtimer_interrupt(). Signed-off-by:
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Thomas Gleixner authored
commit 196951e9 upstream. We need to update the base offsets from this code and we need to do that under base->lock. Move the lock held region around the ktime_get() calls. The ktime_get() calls are going to be replaced with a function which gets the time and the offsets atomically. Signed-off-by:
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Thomas Gleixner authored
This is a backport of 5b9fe759 We need to update the hrtimer clock offsets from the hrtimer interrupt context. To avoid conversions from timespec to ktime_t maintain a ktime_t based representation of those offsets in the timekeeper. This puts the conversion overhead into the code which updates the underlying offsets and provides fast accessible values in the hrtimer interrupt. Signed-off-by:
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