- 13 Oct, 2018 1 commit
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Federico Motta authored
bfq defines as asymmetric a scenario where an active entity, say E (representing either a single bfq_queue or a group of other entities), has a higher weight than some other entities. If the entity E does sync I/O in such a scenario, then bfq plugs the dispatch of the I/O of the other entities in the following situation: E is in service but temporarily has no pending I/O request. In fact, without this plugging, all the times that E stops being temporarily idle, it may find the internal queues of the storage device already filled with an out-of-control number of extra requests, from other entities. So E may have to wait for the service of these extra requests, before finally having its own requests served. This may easily break service guarantees, with E getting less than its fair share of the device throughput. Usually, the end result is that E gets the same fraction of the throughput as the other entities, instead of getting more, according to its higher weight. Yet there are two other more subtle cases where E, even if its weight is actually equal to or even lower than the weight of any other active entities, may get less than its fair share of the throughput in case the above I/O plugging is not performed: 1. other entities issue larger requests than E; 2. other entities contain more active child entities than E (or in general tend to have more backlog than E). In the first case, other entities may get more service than E because they get larger requests, than those of E, served during the temporary idle periods of E. In the second case, other entities get more service because, by having many child entities, they have many requests ready for dispatching while E is temporarily idle. This commit addresses this issue by extending the definition of asymmetric scenario: a scenario is asymmetric when - active entities representing bfq_queues have differentiated weights, as in the original definition or (inclusive) - one or more entities representing groups of entities are active. This broader definition makes sure that I/O plugging will be performed in all the above cases, provided that there is at least one active group. Of course, this definition is very coarse, so it will trigger I/O plugging also in cases where it is not needed, such as, e.g., multiple active entities with just one child each, and all with the same I/O-request size. The reason for this coarse definition is just that a finer-grained definition would be rather heavy to compute. On the opposite end, even this new definition does not trigger I/O plugging in all cases where there is no active group, and all bfq_queues have the same weight. So, in these cases some unfairness may occur if there are asymmetries in I/O-request sizes. We made this choice because I/O plugging may lower throughput, and probably a user that has not created any group cares more about throughput than about perfect fairness. At any rate, as for possible applications that may care about service guarantees, bfq already guarantees a high responsiveness and a low latency to soft real-time applications automatically. Signed-off-by:
Federico Motta <federico@willer.it> Signed-off-by:
Paolo Valente <paolo.valente@linaro.org> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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- 11 Oct, 2018 2 commits
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Maciej S. Szmigiero authored
BFQ is already doing a similar thing in its .pd_offline_fn() method implementation. While it seems that after commit 4c699480 ("blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()") was reverted leaving these pointers intact no longer causes crashes clearing them is still a sensible thing to do to make the code more robust. Signed-off-by:
Maciej S. Szmigiero <mail@maciej.szmigiero.name> Signed-off-by:
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Konstantin Khlebnikov authored
This adds reasonable comments, but they definitely needs better names. Signed-off-by:
Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by:
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- 10 Oct, 2018 2 commits
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Bartlomiej Zolnierkiewicz authored
'default n' is the default value for any bool or tristate Kconfig setting so there is no need to write it explicitly. Also since commit f467c564 ("kconfig: only write '# CONFIG_FOO is not set' for visible symbols") the Kconfig behavior is the same regardless of 'default n' being present or not: ... One side effect of (and the main motivation for) this change is making the following two definitions behave exactly the same: config FOO bool config FOO bool default n With this change, neither of these will generate a '# CONFIG_FOO is not set' line (assuming FOO isn't selected/implied). That might make it clearer to people that a bare 'default n' is redundant. ... Signed-off-by:
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by:
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Bartlomiej Zolnierkiewicz authored
'default n' is the default value for any bool or tristate Kconfig setting so there is no need to write it explicitly. Also since commit f467c564 ("kconfig: only write '# CONFIG_FOO is not set' for visible symbols") the Kconfig behavior is the same regardless of 'default n' being present or not: ... One side effect of (and the main motivation for) this change is making the following two definitions behave exactly the same: config FOO bool config FOO bool default n With this change, neither of these will generate a '# CONFIG_FOO is not set' line (assuming FOO isn't selected/implied). That might make it clearer to people that a bare 'default n' is redundant. ... Signed-off-by:
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- 09 Oct, 2018 35 commits
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Javier González authored
pblk's write buffer must guarantee that it respects the device's constrains for reads (i.e., mw_cunits). This is done by maintaining a backpointer that updates the L2P table as entries wrap up, making them point to the media instead of pointing to the write buffer. This mechanism can race in case that the write thread stalls, as the write pointer will protect the last written entry, thus disregarding the read constrains. This patch adds an extra check on wrap up, making sure that the threshold is respected at all times, preventing new entries to overwrite committed data, also in case of write thread stall. Reported-by:
Heiner Litz <hlitz@ucsc.edu> Signed-off-by:
Javier González <javier@cnexlabs.com> Reviewed-by:
Matias Bjørling <mb@lightnvm.io> Signed-off-by:
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Zhoujie Wu authored
When do GC, the number of read/write sectors are determined by max_write_pgs(see gc_rq preparation in pblk_gc_line_prepare_ws). Due to max_write_pgs doesn't consider max hw sectors supported by nvme controller(128K), which leads to GC tries to read 64 * 4K in one command, and see below error caused by pblk_bio_map_addr in function pblk_submit_read_gc. [ 2923.005376] pblk: could not add page to bio [ 2923.005377] pblk: could not allocate GC bio (18446744073709551604) Signed-off-by:
Zhoujie Wu <zjwu@marvell.com> Reviewed-by:
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Wei Yongjun authored
In the too many bad blocks error handling case, we should release all the allocated resources, otherwise it will cause memory leak. Fixes: 2deeefc0 ("lightnvm: pblk: fail gracefully on line alloc. failure") Signed-off-by:
Wei Yongjun <weiyongjun1@huawei.com> Reviewed-by:
Hans Holmberg <hans.holmberg@cnexlabs.com> Signed-off-by:
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Javier González authored
1.2 devices exposes their data and metadata size through the separate identify command. Make sure that the NVMe LBA format does not override these values. Signed-off-by:
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Javier González authored
OCSSD 2.0 defines the amount of data that the host must buffer per chunk to guarantee reads through the geometry field mw_cunits. This value is the base that pblk uses to determine the size of its read buffer. Currently, this size is set to be the closes power-of-2 to mw_cunits times the number of parallel units available to the pblk instance for each open line (currently one). When an entry (4KB) is put in the buffer, the L2P table points to it. As the buffer wraps up, the L2P is updated to point to addresses on the device, thus guaranteeing mw_cunits at a chunk level. However, given that pblk cannot write to the device under ws_min (normally ws_opt), there might be a window in which the buffer starts wrapping up and updating L2P entries before the mw_cunits value in a chunk has been surpassed. In order not to violate the mw_cunits constrain in this case, account for ws_opt on the read buffer creation. Signed-off-by:
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Javier González authored
pblk's read/write buffer currently takes a buffer and its size and uses it to create the metadata around it to use it as a ring buffer. This puts the responsibility of allocating/freeing ring buffer memory on the ring buffer user. Instead, move it inside of the ring buffer helpers (pblk-rb.c). This simplifies creation/destruction routines. Signed-off-by:
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Javier González authored
pblk's read/write buffer is always a power-of-2, thus wrapping up the buffer can be done with a bit mask. Since this is an implementation detail internal to the write buffer, make a helper that hides pointer increment + wrap, and allows to transparently relax this assumption in the future. Signed-off-by:
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Javier González authored
Removed unused function in pblk-rb.c Signed-off-by:
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Javier González authored
pblk exposes a sysfs interface that represents its internal state. Part of this state is the map bitmap for the current open line, which should be protected by the line lock to avoid a race when freeing the line metadata. Currently, it is not. This patch makes sure that the line state is consistent and NULL bitmap pointers are not dereferenced. Signed-off-by:
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Javier González authored
Add GLP-2.0 SPDX license tag to all pblk files Signed-off-by:
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Javier González authored
In the OCSSD 2.0 spec, each chunk reports its write pointer. This means that pblk does not need to scan open lines to find the write pointer, but instead, it can retrieve it directly (and verify it). This patch uses the write pointer on open lines to (i) recover the line up until the last written lba and (ii) reconstruct the map bitmap and rest of line metadata so that the line can be used for new data. Since the 1.2 path in lightnvm core has been re-implemented to populate the chunk structure and thus recover the write pointer on initialization, this patch removes 1.2 specific recovery, as the 2.0 path can be reused. Signed-off-by:
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Javier González authored
pblk guarantees write ordering at a chunk level through a per open chunk semaphore. At this point, since we only have an open I/O stream for both user and GC data, the semaphore is per parallel unit. For the metadata I/O that is synchronous, the semaphore is not needed as ordering is guaranteed. However, if the metadata scheme changes or multiple streams are open, this guarantee might not be preserved. This patch makes sure that all writes go through the semaphore, even for synchronous I/O. This is consistent with pblk's write I/O model. It also simplifies maintenance since changes in the metadata scheme could cause ordering issues. Signed-off-by:
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Javier González authored
pblk maintains two different metadata paths for smeta and emeta, which store metadata at the start of the line and at the end of the line, respectively. Until now, these path has been common for writing and retrieving metadata, however, as these paths diverge, the common code becomes less clear and unnecessary complicated. In preparation for further changes to the metadata write path, this patch separates the write and read paths for smeta and emeta and removes the synchronous emeta path as it not used anymore (emeta is scheduled asynchronously to prevent jittering due to internal I/Os). Signed-off-by:
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Javier González authored
dma allocations for ppa_list and meta_list in rqd are replicated in several places across the pblk codebase. Make helpers to encapsulate creation and deletion to simplify the code. Signed-off-by:
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Javier González authored
The lightnvm subsystem provides helpers to retrieve chunk metadata, where the target needs to provide a buffer to store the metadata. An implicit assumption is that this buffer is contiguous and can be used to retrieve the data from the device. If the device exposes too many chunks, then kmalloc might fail, thus failing instance creation. This patch removes this assumption by implementing an internal buffer in the lightnvm subsystem to retrieve chunk metadata. Targets can then use virtual memory allocations. Since this is a target API change, adapt pblk accordingly. Signed-off-by:
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Jia-Ju Bai authored
The driver may sleep with holding a spinlock. The function call paths (from bottom to top) in Linux-4.16 are: [FUNC] nvm_dev_dma_alloc(GFP_KERNEL) drivers/lightnvm/pblk-core.c, 754: nvm_dev_dma_alloc in pblk_line_submit_smeta_io drivers/lightnvm/pblk-core.c, 1048: pblk_line_submit_smeta_io in pblk_line_init_bb drivers/lightnvm/pblk-core.c, 1434: pblk_line_init_bb in pblk_line_replace_data drivers/lightnvm/pblk-recovery.c, 980: pblk_line_replace_data in pblk_recov_l2p drivers/lightnvm/pblk-recovery.c, 976: spin_lock in pblk_recov_l2p [FUNC] bio_map_kern(GFP_KERNEL) drivers/lightnvm/pblk-core.c, 762: bio_map_kern in pblk_line_submit_smeta_io drivers/lightnvm/pblk-core.c, 1048: pblk_line_submit_smeta_io in pblk_line_init_bb drivers/lightnvm/pblk-core.c, 1434: pblk_line_init_bb in pblk_line_replace_data drivers/lightnvm/pblk-recovery.c, 980: pblk_line_replace_data in pblk_recov_l2p drivers/lightnvm/pblk-recovery.c, 976: spin_lock in pblk_recov_l2p To fix these bugs, the call to pblk_line_replace_data() is moved out of the spinlock protection. These bugs are found by my static analysis tool DSAC. Signed-off-by:
Jia-Ju Bai <baijiaju1990@gmail.com> Reviewed-by:
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Hans Holmberg authored
On 1.2-devices, the mapping-out of remaning sectors in the failed-write's block can result in an infinite loop, stalling the write pipeline, fix this. Fixes: 6a3abf5b ("lightnvm: pblk: rework write error recovery path") Signed-off-by:
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Hans Holmberg authored
Pblk should not create a set of global caches every time a pblk instance is created. The global caches should be made available only when there is one or more pblk instances. This patch bundles the global caches together with a kref keeping track of whether the caches should be available or not. Also, turn the global pblk lock into a mutex that explicitly protects the caches (as this was the only purpose of the lock). Signed-off-by:
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Javier González authored
If a line is padded, calculate the pad distance directly on the helper being used for this purpose. Signed-off-by:
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Javier González authored
Continuing the effort of moving 1.2 and 2.0 specific code to core, move 64_to_32 and 32_to_64 ppa helpers from pblk to core. Signed-off-by:
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Hans Holmberg authored
Trace state of chunk resets. Signed-off-by:
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Hans Holmberg authored
Add trace events for tracking pblk state changes. Signed-off-by:
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Hans Holmberg authored
Add trace events for logging for line state changes. Signed-off-by:
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Hans Holmberg authored
Introduce trace points for tracking chunk states in pblk - this is useful for inspection of the entire state of the drive, and real handy for both fw and pblk debugging. Signed-off-by:
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Matias Bjørling authored
Remove the debug only iteration within __pblk_down_page, which then allows us to reduce the number of arguments down to pblk and the parallel unit from the functions that calls it. Simplifying the callers logic considerably. Also, rename the functions pblk_[down/up]_page to pblk_[down/up]_chunk, to communicate that it manages the write pointer of the chunk. Note that it also protects the parallel unit such that at most one chunk is active per parallel unit. Signed-off-by:
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Hans Holmberg authored
When the user data counter exceeds 32 bits, the write amplification calculation does not provide the right value. Fix this by using div64_u64 in stead of div64. Fixes: 76758390 ("lightnvm: pblk: export write amplification counters to sysfs") Signed-off-by:
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Hans Holmberg authored
The prefix when printing ppas in pblk_read_check_rand should be "rnd" not "seq", so fix this so we can differentiate between lba missmatches in random and sequential reads. Also change the print order so we align with pblk_read_check_seq, printing read lba first. Signed-off-by:
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Hans Holmberg authored
The parameters nr_ppas and ppa_list are not used, so remove them. Signed-off-by:
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Hans Holmberg authored
Line map bitmap allocations are fairly large and can fail. Allocation failures are fatal to pblk, stopping the write pipeline. To avoid this, allocate the bitmaps using a mempool instead. Mempool allocations never fail if called from a process context, and pblk *should* only allocate map bitmaps in process context, but keep the failure handling for robustness sake. Signed-off-by:
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Hans Holmberg authored
There is a number of places in the lightnvm subsystem where the user iterates over the ppa list. Before iterating, the user must know if it is a single or multiple LBAs due to vector commands using either the nvm_rq ->ppa_addr or ->ppa_list fields on command submission, which leads to open-coding the if/else statement. Instead of having multiple if/else's, move it into a function that can be called by its users. A nice side effect of this cleanup is that this patch fixes up a bunch of cases where we don't consider the single-ppa case in pblk. Signed-off-by:
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Javier González authored
If a line is recovered from open chunks, the memory structures for emeta have not necessarily been properly set on line initialization. When closing a line, make sure that emeta is consistent so that the line can be recovered on the fast path on next reboot. Also, remove a couple of empty lines at the end of the function. Signed-off-by:
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Javier González authored
Removed unused struct ppa_addr variable. Signed-off-by:
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Javier González authored
Fix comment typo Decrese -> Decrease Signed-off-by:
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Javier González authored
The current helper to obtain a line from a ppa returns the line id, which requires its users to explicitly retrieve the pointer to the line with the id. Make 2 different helpers: one returning the line id and one returning the line directly. Signed-off-by:
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Javier González authored
Implement helpers to go from ppas to a chunk within a line and an address within a chunk. These helpers will be used on the patches adding trace support in pblk, which will be sent in this window. Signed-off-by:
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