- 20 Oct, 2021 6 commits
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Ming Lei authored
blk_mq_quiesce_queue() has been used a bit wide now, so far we don't support concurrent/nested quiesce. One biggest issue is that unquiesce can happen unexpectedly in case that quiesce/unquiesce are run concurrently from more than one context. This patch introduces q->mq_quiesce_depth to deal concurrent quiesce, and we only unquiesce queue when it is the last/outer-most one of all contexts. Several kernel panic issue has been reported[1][2][3] when running stress quiesce test. And this patch has been verified in these reports. [1] https://lore.kernel.org/linux-block/9b21c797-e505-3821-4f5b-df7bf9380328@huawei.com/T/#m1fc52431fad7f33b1ffc3f12c4450e4238540787 [2] https://lore.kernel.org/linux-block/9b21c797-e505-3821-4f5b-df7bf9380328@huawei.com/T/#m10ad90afeb9c8cc318334190a7c24c8b5c5e0722 [3] https://listman.redhat.com/archives/dm-devel/2021-September/msg00189.htmlSigned-off-by:
Ming Lei <ming.lei@redhat.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211014081710.1871747-7-ming.lei@redhat.comSigned-off-by:
Jens Axboe <axboe@kernel.dk>
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Ming Lei authored
The nvme-loop's admin queue may be freed and reallocated, and we have to reset the flag of NVME_CTRL_ADMIN_Q_STOPPED so that the flag can match with the quiesce state of the admin queue. nvme-loop is the only driver to reallocate request queue, and not see such usage in other nvme drivers. Signed-off-by:
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Ming Lei authored
The current blk_mq_quiesce_queue() and blk_mq_unquiesce_queue() always stops and starts the queue unconditionally. And there can be concurrent quiesce/unquiesce coming from different unrelated code paths, so unquiesce may come unexpectedly and start queue too early. Prepare for supporting concurrent quiesce/unquiesce from multiple contexts, so that we can address the above issue. NVMe has very complicated quiesce/unquiesce use pattern, add one atomic bit for makeiing sure that blk-mq quiece/unquiesce is always called in pair. Signed-off-by:
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Ming Lei authored
Add two helpers so that we can prepare for pairing quiescing and unquiescing which will be done in next patch. Signed-off-by:
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Ming Lei authored
Apply the added two APIs to quiesce/unquiesce admin queue. Signed-off-by:
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Ming Lei authored
Add two APIs for stopping and starting admin queue. Signed-off-by:
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- 19 Oct, 2021 13 commits
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Zheng Liang authored
In bfq_pd_alloc(), the function bfqg_stats_init() init bfqg. If blkg_rwstat_init() init bfqg_stats->bytes successful and init bfqg_stats->ios failed, bfqg_stats_init() return failed, bfqg will be freed. But blkg_rwstat->cpu_cnt is not deleted from the list of percpu_counters. If we traverse the list of percpu_counters, It will have UAF problem. we should use blkg_rwstat_exit() to cleanup bfqg_stats bytes in the above scenario. Fixes: commit fd41e603 ("bfq-iosched: stop using blkg->stat_bytes and ->stat_ios") Signed-off-by:
Zheng Liang <zhengliang6@huawei.com> Acked-by:
Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20211018024225.1493938-1-zhengliang6@huawei.comSigned-off-by:
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Jens Axboe authored
If we don't use an IO scheduler or have shared tags, then we don't need to call into this external function at all. This saves ~2% for such a setup. Signed-off-by: -
Christoph Hellwig authored
Return to the normal blk_mq_submit_bio flow if the bio did not end up actually being a flush because the device didn't support it. Note that this is basically impossible to hit without special instrumentation given that submit_bio_checks already clears these flags usually, so we'd need a tight race to actually hit this code path. With this the call to blk_mq_run_hw_queue for the flush requests can be removed given that the actual flush requests are always issued via the requeue workqueue which runs the queue unconditionally. Signed-off-by:
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Jens Axboe authored
If we have just one queue type in the plug list, then we can extend our direct issue to cover a full plug list as well. This allows sending a batch of requests for direct issue, which is more efficient than doing one-at-a-time kind of issue. Reviewed-by:
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Jens Axboe authored
Use a singly linked list for the blk_plug. This saves 8 bytes in the blk_plug struct, and makes for faster list manipulations than doubly linked lists. As we don't use the doubly linked lists for anything, singly linked is just fine. This yields a bump in default (merging enabled) performance from 7.0 to 7.1M IOPS, and ~7.5M IOPS with merging disabled. Reviewed-by:
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Andrea Righi authored
The timer callback used to evaluate if the latency is exceeded can be executed after the corresponding disk has been released, causing the following NULL pointer dereference: [ 119.987108] BUG: kernel NULL pointer dereference, address: 0000000000000098 [ 119.987617] #PF: supervisor read access in kernel mode [ 119.987971] #PF: error_code(0x0000) - not-present page [ 119.988325] PGD 7c4a4067 P4D 7c4a4067 PUD 7bf63067 PMD 0 [ 119.988697] Oops: 0000 [#1] SMP NOPTI [ 119.988959] CPU: 1 PID: 9353 Comm: cloud-init Not tainted 5.15-rc5+arighi #rc5+arighi [ 119.989520] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 [ 119.990055] RIP: 0010:wb_timer_fn+0x44/0x3c0 [ 119.990376] Code: 41 8b 9c 24 98 00 00 00 41 8b 94 24 b8 00 00 00 41 8b 84 24 d8 00 00 00 4d 8b 74 24 28 01 d3 01 c3 49 8b 44 24 60 48 8b 40 78 <4c> 8b b8 98 00 00 00 4d 85 f6 0f 84 c4 00 00 00 49 83 7c 24 30 00 [ 119.991578] RSP: 0000:ffffb5f580957da8 EFLAGS: 00010246 [ 119.991937] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004 [ 119.992412] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88f476d7f780 [ 119.992895] RBP: ffffb5f580957dd0 R08: 0000000000000000 R09: 0000000000000000 [ 119.993371] R10: 0000000000000004 R11: 0000000000000002 R12: ffff88f476c84500 [ 119.993847] R13: ffff88f4434390c0 R14: 0000000000000000 R15: ffff88f4bdc98c00 [ 119.994323] FS: 00007fb90bcd9c00(0000) GS:ffff88f4bdc80000(0000) knlGS:0000000000000000 [ 119.994952] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 119.995380] CR2: 0000000000000098 CR3: 000000007c0d6000 CR4: 00000000000006e0 [ 119.995906] Call Trace: [ 119.996130] ? blk_stat_free_callback_rcu+0x30/0x30 [ 119.996505] blk_stat_timer_fn+0x138/0x140 [ 119.996830] call_timer_fn+0x2b/0x100 [ 119.997136] __run_timers.part.0+0x1d1/0x240 [ 119.997470] ? kvm_clock_get_cycles+0x11/0x20 [ 119.997826] ? ktime_get+0x3e/0xa0 [ 119.998110] ? native_apic_msr_write+0x2c/0x30 [ 119.998456] ? lapic_next_event+0x20/0x30 [ 119.998779] ? clockevents_program_event+0x94/0xf0 [ 119.999150] run_timer_softirq+0x2a/0x50 [ 119.999465] __do_softirq+0xcb/0x26f [ 119.999764] irq_exit_rcu+0x8c/0xb0 [ 120.000057] sysvec_apic_timer_interrupt+0x43/0x90 [ 120.000429] ? asm_sysvec_apic_timer_interrupt+0xa/0x20 [ 120.000836] asm_sysvec_apic_timer_interrupt+0x12/0x20 In this case simply return from the timer callback (no action required) to prevent the NULL pointer dereference. BugLink: https://bugs.launchpad.net/bugs/1947557 Link: https://lore.kernel.org/linux-mm/YWRNVTk9N8K0RMst@arighi-desktop/ Fixes: 34dbad5d ("blk-stat: convert to callback-based statistics reporting") Signed-off-by:
Andrea Righi <andrea.righi@canonical.com> Link: https://lore.kernel.org/r/YW6N2qXpBU3oc50q@arighi-desktopSigned-off-by:
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Jens Axboe authored
We get all sorts of unreliable and funky results since the bio is designed to align on a cacheline, which it does not when inlined like this. Reviewed-by:
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Jens Axboe authored
This is in the fast path of driver issue or completion, and it's a single array index operation. Move it inline to avoid a function call for it. This does mean making struct blk_mq_tags block layer public, but there's not really much in there. Reviewed-by:
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Jens Axboe authored
Even if we have multiple queues in the plug list, chances that they are very interspersed is minimal. Don't bother spending CPU cycles sorting the list. Reviewed-by:
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Jens Axboe authored
Instead of returning the same queue request through a request pointer, use a boolean to accomplish the same. Reviewed-by:
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Christoph Hellwig authored
We only need to call it to resolve the blk_status_t -> errno mapping for tracing, so move the conversion into the tracepoints that are not called at all when tracing isn't enabled. Signed-off-by:
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Jens Axboe authored
This is called for every write in the fast path, move it inline next to get_disk_ro() which is called internally. Reviewed-by:
Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by:
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Jens Axboe authored
We added RQF_ELV to tell whether there's an IO scheduler attached, and RQF_ELVPRIV tells us whether there's an IO scheduler with private data attached. Don't check RQF_ELV in blk_mq_free_request(), what we care about here is just if we have scheduler private data attached. This fixes a boot crash Fixes: 2ff0682d ("block: store elevator state in request") Reported-by:
Yi Zhang <yi.zhang@redhat.com> Reported-by: syzbot+eb8104072aeab6cc1195@syzkaller.appspotmail.com Signed-off-by:
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- 18 Oct, 2021 21 commits
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Jens Axboe authored
Trivial to do now, just need our own io_comp_batch on the stack and pass that in to the usual command completion handling. I pondered making this dependent on how many entries we had to process, but even for a single entry there's no discernable difference in performance or latency. Running a sync workload over io_uring: t/io_uring -b512 -d1 -s1 -c1 -p0 -F1 -B1 -n2 /dev/nvme1n1 /dev/nvme2n1 yields the below performance before the patch: IOPS=254820, BW=124MiB/s, IOS/call=1/1, inflight=(1 1) IOPS=251174, BW=122MiB/s, IOS/call=1/1, inflight=(1 1) IOPS=250806, BW=122MiB/s, IOS/call=1/1, inflight=(1 1) and the following after: IOPS=255972, BW=124MiB/s, IOS/call=1/1, inflight=(1 1) IOPS=251920, BW=123MiB/s, IOS/call=1/1, inflight=(1 1) IOPS=251794, BW=122MiB/s, IOS/call=1/1, inflight=(1 1) which definitely isn't slower, about the same if you factor in a bit of variance. For peak performance workloads, benchmarking shows a 2% improvement. Reviewed-by:
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Jens Axboe authored
Wire up using an io_comp_batch for f_op->iopoll(). If the lower stack supports it, we can handle high rates of polled IO more efficiently. This raises the single core efficiency on my system from ~6.1M IOPS to ~6.6M IOPS running a random read workload at depth 128 on two gen2 Optane drives. Reviewed-by:
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Jens Axboe authored
Take advantage of struct io_comp_batch, if passed in to the nvme poll handler. If it's set, rather than complete each request individually inline, store them in the io_comp_batch list. We only do so for requests that will complete successfully, anything else will be completed inline as before. Reviewed-by:
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Jens Axboe authored
Instead of calling blk_mq_end_request() on a single request, add a helper that takes the new struct io_comp_batch and completes any request stored in there. Reviewed-by:
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Jens Axboe authored
sbitmap currently only supports clearing tags one-by-one, add a helper that allows the caller to pass in an array of tags to clear. Signed-off-by: -
Jens Axboe authored
struct io_comp_batch contains a list head and a completion handler, which will allow completions to more effciently completed batches of IO. For now, no functional changes in this patch, we just define the io_comp_batch structure and add the argument to the file_operations iopoll handler. Reviewed-by:
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Jens Axboe authored
Instead of open-coding the list additions, traversal, and removal, provide a basic set of helpers. Suggested-by:
Christoph Hellwig <hch@infradead.org> Signed-off-by:
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Jens Axboe authored
Just like the blk_mq_ctx counterparts, we've got a bunch of counters in here that are only for debugfs and are of questionnable value. They are: - dispatched, index of how many requests were dispatched in one go - poll_{considered,invoked,success}, which track poll sucess rates. We're confident in the iopoll implementation at this point, don't bother tracking these. As a bonus, this shrinks each hardware queue from 576 bytes to 512 bytes, dropping a whole cacheline. Reviewed-by: -
Jens Axboe authored
These were added as part of early days debugging for blk-mq, and they are not really useful anymore. Rather than spend cycles updating them, just get rid of them. As a bonus, this shrinks the per-cpu software queue size from 256b to 192b. That's a whole cacheline less. Reviewed-by:
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Pavel Begunkov authored
Add a local variable for rq_flags, it helps to compile out some of rq_flags reloads. Signed-off-by:
Pavel Begunkov <asml.silence@gmail.com> Signed-off-by:
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Pavel Begunkov authored
We should have enough of registers in blk_mq_rq_ctx_init(), store them in local vars, so we don't keep reloading them. note: keeping q->elevator may look unnecessary, but it's also used inside inlined blk_mq_tags_from_data(). Signed-off-by:
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Pavel Begunkov authored
Don't init rq->hash and rq->rb_node in blk_mq_rq_ctx_init() if there is no elevator. Also, move some other initialisers that imply barriers to the end, so the compiler is free to rearrange and optimise other the rest of them. note: fold in a change from Jens leaving queue_list unconditional, as it might lead to problems otherwise. Signed-off-by:
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Jens Axboe authored
Add an rq private RQF_ELV flag, which tells the block layer that this request was initialized on a queue that has an IO scheduler attached. This allows for faster checking in the fast path, rather than having to deference rq->q later on. Elevator switching does full quiesce of the queue before detaching an IO scheduler, so it's safe to cache this in the request itself. Signed-off-by: -
Jens Axboe authored
We set BIO_TRACKED unconditionally when rq_qos_throttle() is called, even though we may not even have an rq_qos handler. Only mark it as TRACKED if it really is potentially tracked. This saves considerable time for the case where the bio isn't tracked: 2.64% -1.65% [kernel.vmlinux] [k] bio_endio Reviewed-by: -
Jens Axboe authored
It's been a while since this was analyzed, move some members around to better flow with the use case. Initial state up top, and queued state after that. This improves my peak case by about 1.5%, from 7750K to 7900K IOPS. Reviewed-by:
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Jens Axboe authored
For some reason we still have them in blk-core, with the rest of the request completion being in blk-mq. That causes and out-of-line call for each completion. Move them into blk-mq.c instead, where they belong. Reviewed-by:
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Jens Axboe authored
We have exactly one caller of this, just get rid of adding the useless function name to the output. Reviewed-by:
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Jens Axboe authored
If we're completing nbytes and nbytes is the size of the bio, don't bother with calling into the iterator increment helpers. Just clear the bio size and we're done. Reviewed-by:
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Pavel Begunkov authored
Convert bdev->bd_disk->queue to bdev_get_queue(), it's uses a cached queue pointer and so is faster. Signed-off-by:
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Pavel Begunkov authored
Convert bdev->bd_disk->queue to bdev_get_queue(), it's uses a cached queue pointer and so is faster. Signed-off-by:
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Pavel Begunkov authored
Convert bdev->bd_disk->queue to bdev_get_queue(), it's uses a cached queue pointer and so is faster. Signed-off-by:
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