- 10 Nov, 2016 8 commits
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Jens Axboe authored
Enable throttling of buffered writeback to make it a lot more smooth, and has way less impact on other system activity. Background writeback should be, by definition, background activity. The fact that we flush huge bundles of it at the time means that it potentially has heavy impacts on foreground workloads, which isn't ideal. We can't easily limit the sizes of writes that we do, since that would impact file system layout in the presence of delayed allocation. So just throttle back buffered writeback, unless someone is waiting for it. The algorithm for when to throttle takes its inspiration in the CoDel networking scheduling algorithm. Like CoDel, blk-wb monitors the minimum latencies of requests over a window of time. In that window of time, if the minimum latency of any request exceeds a given target, then a scale count is incremented and the queue depth is shrunk. The next monitoring window is shrunk accordingly. Unlike CoDel, if we hit a window that exhibits good behavior, then we simply increment the scale count and re-calculate the limits for that scale value. This prevents us from oscillating between a close-to-ideal value and max all the time, instead remaining in the windows where we get good behavior. Unlike CoDel, blk-wb allows the scale count to to negative. This happens if we primarily have writes going on. Unlike positive scale counts, this doesn't change the size of the monitoring window. When the heavy writers finish, blk-bw quickly snaps back to it's stable state of a zero scale count. The patch registers a sysfs entry, 'wb_lat_usec'. This sets the latency target to me met. It defaults to 2 msec for non-rotational storage, and 75 msec for rotational storage. Setting this value to '0' disables blk-wb. Generally, a user would not have to touch this setting. We don't enable WBT on devices that are managed with CFQ, and have a non-root block cgroup attached. If we have a proportional share setup on this particular disk, then the wbt throttling will interfere with that. We don't have a strong need for wbt for that case, since we will rely on CFQ doing that for us. Signed-off-by:Jens Axboe <axboe@fb.com>
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Jens Axboe authored
We can hook this up to the block layer, to help throttle buffered writes. wbt registers a few trace points that can be used to track what is happening in the system: wbt_lat: 259:0: latency 2446318 wbt_stat: 259:0: rmean=2446318, rmin=2446318, rmax=2446318, rsamples=1, wmean=518866, wmin=15522, wmax=5330353, wsamples=57 wbt_step: 259:0: step down: step=1, window=72727272, background=8, normal=16, max=32 This shows a sync issue event (wbt_lat) that exceeded it's time. wbt_stat dumps the current read/write stats for that window, and wbt_step shows a step down event where we now scale back writes. Each trace includes the device, 259:0 in this case. Signed-off-by: -
Jens Axboe authored
For legacy block, we simply track them in the request queue. For blk-mq, we track them on a per-sw queue basis, which we can then sum up through the hardware queues and finally to a per device state. The stats are tracked in, roughly, 0.1s interval windows. Add sysfs files to display the stats. The feature is off by default, to avoid any extra overhead. In-kernel users of it can turn it on by setting QUEUE_FLAG_STATS in the queue flags. We currently don't turn it on if someone just reads any of the stats files, that is something we could add as well. Signed-off-by: -
Tejun Heo authored
cfq_cpd_alloc() which is the cpd_alloc_fn implementation for cfq was incorrectly hard coding GFP_KERNEL instead of using the mask specified through the @gfp parameter. This currently doesn't cause any actual issues because all current callers specify GFP_KERNEL. Fix it. Signed-off-by:
Tejun Heo <tj@kernel.org> Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Fixes: e4a9bde9 ("blkcg: replace blkcg_policy->cpd_size with ->cpd_alloc/free_fn() methods") Signed-off-by:
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Christoph Hellwig authored
We only need the status and result fields, and passing them explicitly makes life a lot easier for the Fibre Channel transport which doesn't have a full CQE for the fast path case. Signed-off-by:
Christoph Hellwig <hch@lst.de> Reviewed-by:
Keith Busch <keith.busch@intel.com> Signed-off-by:
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Christoph Hellwig authored
This adds a shared per-request structure for all NVMe I/O. This structure is embedded as the first member in all NVMe transport drivers request private data and allows to implement common functionality between the drivers. The first use is to replace the current abuse of the SCSI command passthrough fields in struct request for the NVMe command passthrough, but it will grow a field more fields to allow implementing things like common abort handlers in the future. The passthrough commands are handled by having a pointer to the SQE (struct nvme_command) in struct nvme_request, and the union of the possible result fields, which had to be turned from an anonymous into a named union for that purpose. This avoids having to pass a reference to a full CQE around and thus makes checking the result a lot more lightweight. Signed-off-by:
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Arnd Bergmann authored
Building with W=1 shows a harmless warning for the skd driver: drivers/block/skd_main.c:2959:1: error: ‘static’ is not at beginning of declaration [-Werror=old-style-declaration] This changes the prototype to the expected formatting. Signed-off-by:
Arnd Bergmann <arnd@arndb.de> Signed-off-by:
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Arnd Bergmann authored
As reported by gcc -Wmaybe-uninitialized, the cleanup path for skd_acquire_msix tries to free the already allocated msi-x vectors in reverse order, but the index variable may not have been used yet: drivers/block/skd_main.c: In function ‘skd_acquire_irq’: drivers/block/skd_main.c:3890:8: error: ‘i’ may be used uninitialized in this function [-Werror=maybe-uninitialized] This changes the failure path to skip releasing the interrupts if we have not started requesting them yet. Fixes: 180b0ae7 ("skd: use pci_alloc_irq_vectors") Signed-off-by:
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- 09 Nov, 2016 1 commit
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Jens Axboe authored
If we insert a flush request, we clear REQ_PREFLUSH and/or REQ_FUA, depending on flush settings. Since op_is_sync() factors those flags in for deciding whether this request is sync or not, we should set REQ_SYNC to avoid screwing up this accounting. This should be less fragile. Reported-by:
Logan Gunthorpe <logang@deltatee.com> Fixes: b685d3d6 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous") Signed-off-by:
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- 08 Nov, 2016 3 commits
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Jens Axboe authored
Note in the bdi_writeback structure whenever a task ends up sleeping waiting for progress. We can use that information in the lower layers to increase the priority of writes. Signed-off-by:
Jan Kara <jack@suse.cz>
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Andy Shevchenko authored
Replace custom approach by %*ph specifier to dump small buffers in hex format. Unfortunately we can't use print_hex_dump_bytes() here since tha gap is present, though one familiar with the code may change this. Signed-off-by:
Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by:
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Christoph Hellwig authored
Switch the skd driver to use pci_alloc_irq_vectors. We need to two calls to pci_alloc_irq_vectors as skd only supports multiple MSI-X vectors, but not multiple MSI vectors. Otherwise this cleans up a lot of cruft and allows to a lot more common code. Signed-off-by:
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- 07 Nov, 2016 1 commit
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Christoph Hellwig authored
Hi Peter, hi Jens, I've been looking over the multi page bio vec work again recently, and one of the stumbling blocks is raw biovec access in the pktcdvd. The first issue is that it directly sets up the page and offset pointers in the biovec just before calling bio_add_page. As bio_add_page already does the setup it's trivial to just switch it to stack variables for the arguments. The second issue is the copy code in pkt_make_local_copy, which effectively is an opencoded version of bio_copy_data except that it skips pages that already are the same in the ѕource and destination. But we look at the only calleer we just set up the bio using bio_add_page to point exactly to the page array that pkt_make_local_copy compares, so the pages will always be the same and we can just remove this function. Note that all this is done based on code inspection, I don't have any packet writing hardware myself. Signed-off-by:
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- 06 Nov, 2016 1 commit
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Gabriel Krisman Bertazi authored
Commit 0e87e58b ("blk-mq: improve warning for running a queue on the wrong CPU") attempts to avoid triggering the WARN_ON in __blk_mq_run_hw_queue when the expected CPU is dead. Problem is, in the last batch execution before round robin, blk_mq_hctx_next_cpu can schedule a dead CPU and also update next_cpu to the next alive CPU in the mask, which will trigger the WARN_ON despite the previous workaround. The following patch fixes this scenario by always scheduling the value in hctx->next_cpu. This changes the moment when we round-robin the CPU running the hctx, but it really doesn't matter, since it still executes BLK_MQ_CPU_WORK_BATCH times in a row before switching to another CPU. Fixes: 0e87e58b ("blk-mq: improve warning for running a queue on the wrong CPU") Signed-off-by:
Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com> Signed-off-by:
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- 05 Nov, 2016 1 commit
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Jens Axboe authored
For blk-mq, ->nr_requests does track queue depth, at least at init time. But for the older queue paths, it's simply a soft setting. On top of that, it's generally larger than the hardware setting on purpose, to allow backup of requests for merging. Fill a hole in struct request with a 'queue_depth' member, that drivers can call to more closely inform the block layer of the real queue depth. Signed-off-by:
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- 04 Nov, 2016 2 commits
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Shaohua Li authored
This is corresponding part for blk-mq. Disk with multiple hardware queues doesn't need this as we only hold 1 request at most. Signed-off-by:
Shaohua Li <shli@fb.com> Signed-off-by:
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Shaohua Li authored
Currently block plug holds up to 16 non-mergeable requests. This makes sense if the request size is small, eg, reduce lock contention. But if request size is big enough, we don't need to worry about lock contention. Holding such request makes no sense and it lows the disk utilization. In practice, this improves 10% throughput for my raid5 sequential write workload. The size (128k) is arbitrary right now, but it makes sure lock contention is small. This probably could be more intelligent, eg, check average request size holded. Since this is mainly for sequential IO, probably not worthy. V2: check the last request instead of the first request, so as long as there is one big size request we flush the plug. Signed-off-by:
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- 03 Nov, 2016 1 commit
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Johannes Thumshirn authored
bsg_validate_sgv4_hdr() doesn't care about the request_queue, so drop it from it's arguments. Signed-off-by:
Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by:
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- 02 Nov, 2016 16 commits
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Bart Van Assche authored
Make nvme_requeue_req() check BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED. Remove the QUEUE_FLAG_STOPPED manipulations that became superfluous because of this change. Change blk_queue_stopped() tests into blk_mq_queue_stopped(). This patch fixes a race condition: using queue_flag_clear_unlocked() is not safe if any other function that manipulates the queue flags can be called concurrently, e.g. blk_cleanup_queue(). Signed-off-by:
Bart Van Assche <bart.vanassche@sandisk.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Sagi Grimberg <sagi@grimberg.me> Reviewed-by:
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Bart Van Assche authored
Avoid that nvme_queue_rq() is still running when nvme_stop_queues() returns. Signed-off-by:
Sagi Grimberg <sagi@grimberg.me> Reviewed-by:
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Bart Van Assche authored
Ensure that all ongoing dm_mq_queue_rq() and dm_mq_requeue_request() calls have stopped before setting the "queue stopped" flag. This allows to remove the "queue stopped" test from dm_mq_queue_rq() and dm_mq_requeue_request(). This patch fixes a race condition because dm_mq_queue_rq() is called without holding the queue lock and hence BLK_MQ_S_STOPPED can be set at any time while dm_mq_queue_rq() is in progress. This patch prevents that the following hang occurs sporadically when using dm-mq: INFO: task systemd-udevd:10111 blocked for more than 480 seconds. Call Trace: [<ffffffff8161f397>] schedule+0x37/0x90 [<ffffffff816239ef>] schedule_timeout+0x27f/0x470 [<ffffffff8161e76f>] io_schedule_timeout+0x9f/0x110 [<ffffffff8161fb36>] bit_wait_io+0x16/0x60 [<ffffffff8161f929>] __wait_on_bit_lock+0x49/0xa0 [<ffffffff8114fe69>] __lock_page+0xb9/0xc0 [<ffffffff81165d90>] truncate_inode_pages_range+0x3e0/0x760 [<ffffffff81166120>] truncate_inode_pages+0x10/0x20 [<ffffffff81212a20>] kill_bdev+0x30/0x40 [<ffffffff81213d41>] __blkdev_put+0x71/0x360 [<ffffffff81214079>] blkdev_put+0x49/0x170 [<ffffffff812141c0>] blkdev_close+0x20/0x30 [<ffffffff811d48e8>] __fput+0xe8/0x1f0 [<ffffffff811d4a29>] ____fput+0x9/0x10 [<ffffffff810842d3>] task_work_run+0x83/0xb0 [<ffffffff8106606e>] do_exit+0x3ee/0xc40 [<ffffffff8106694b>] do_group_exit+0x4b/0xc0 [<ffffffff81073d9a>] get_signal+0x2ca/0x940 [<ffffffff8101bf43>] do_signal+0x23/0x660 [<ffffffff810022b3>] exit_to_usermode_loop+0x73/0xb0 [<ffffffff81002cb0>] syscall_return_slowpath+0xb0/0xc0 [<ffffffff81624e33>] entry_SYSCALL_64_fastpath+0xa6/0xa8 Signed-off-by:
Mike Snitzer <snitzer@redhat.com> Reviewed-by:
Hannes Reinecke <hare@suse.com> Reviewed-by:
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Bart Van Assche authored
Instead of manipulating both QUEUE_FLAG_STOPPED and BLK_MQ_S_STOPPED in the dm start and stop queue functions, only manipulate the latter flag. Change blk_queue_stopped() tests into blk_mq_queue_stopped(). Signed-off-by:
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Bart Van Assche authored
Most blk_mq_requeue_request() and blk_mq_add_to_requeue_list() calls are followed by kicking the requeue list. Hence add an argument to these two functions that allows to kick the requeue list. This was proposed by Christoph Hellwig. Signed-off-by:
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Bart Van Assche authored
blk_mq_quiesce_queue() waits until ongoing .queue_rq() invocations have finished. This function does *not* wait until all outstanding requests have finished (this means invocation of request.end_io()). The algorithm used by blk_mq_quiesce_queue() is as follows: * Hold either an RCU read lock or an SRCU read lock around .queue_rq() calls. The former is used if .queue_rq() does not block and the latter if .queue_rq() may block. * blk_mq_quiesce_queue() first calls blk_mq_stop_hw_queues() followed by synchronize_srcu() or synchronize_rcu(). The latter call waits for .queue_rq() invocations that started before blk_mq_quiesce_queue() was called. * The blk_mq_hctx_stopped() calls that control whether or not .queue_rq() will be called are called with the (S)RCU read lock held. This is necessary to avoid race conditions against blk_mq_quiesce_queue(). Signed-off-by:
Ming Lei <tom.leiming@gmail.com> Reviewed-by:
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Bart Van Assche authored
Since blk_mq_requeue_work() no longer restarts stopped queues canceling requeue work is no longer needed to prevent that a stopped queue would be restarted. Hence remove this function. Signed-off-by:
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Bart Van Assche authored
Since blk_mq_requeue_work() starts stopped queues and since execution of this function can be scheduled after a queue has been stopped it is not possible to stop queues without using an additional state variable to track whether or not the queue has been stopped. Hence modify blk_mq_requeue_work() such that it does not start stopped queues. My conclusion after a review of the blk_mq_stop_hw_queues() and blk_mq_{delay_,}kick_requeue_list() callers is as follows: * In the dm driver starting and stopping queues should only happen if __dm_suspend() or __dm_resume() is called and not if the requeue list is processed. * In the SCSI core queue stopping and starting should only be performed by the scsi_internal_device_block() and scsi_internal_device_unblock() functions but not by any other function. Although the blk_mq_stop_hw_queue() call in scsi_queue_rq() may help to reduce CPU load if a LLD queue is full, figuring out whether or not a queue should be restarted when requeueing a command would require to introduce additional locking in scsi_mq_requeue_cmd() to avoid a race with scsi_internal_device_block(). Avoid this complexity by removing the blk_mq_stop_hw_queue() call from scsi_queue_rq(). * In the NVMe core only the functions that call blk_mq_start_stopped_hw_queues() explicitly should start stopped queues. * A blk_mq_start_stopped_hwqueues() call must be added in the xen-blkfront driver in its blkif_recover() function. Signed-off-by: -
Bart Van Assche authored
Move the "hctx stopped" test and the insert request calls into blk_mq_direct_issue_request(). Rename that function into blk_mq_try_issue_directly() to reflect its new semantics. Pass the hctx pointer to that function instead of looking it up a second time. These changes avoid that code has to be duplicated in the next patch. Signed-off-by:
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Bart Van Assche authored
The function blk_queue_stopped() allows to test whether or not a traditional request queue has been stopped. Introduce a helper function that allows block drivers to query easily whether or not one or more hardware contexts of a blk-mq queue have been stopped. Signed-off-by:
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Bart Van Assche authored
Multiple functions test the BLK_MQ_S_STOPPED bit so introduce a helper function that performs this test. Signed-off-by:
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Bart Van Assche authored
The meaning of the BLK_MQ_S_STOPPED flag is "do not call .queue_rq()". Hence modify blk_mq_make_request() such that requests are queued instead of issued if a queue has been stopped. Reported-by:
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Kent Overstreet authored
This is a helper that pins down a range from an iov_iter and adds it to a bio without requiring a separate memory allocation for the page array. It will be used for upcoming direct I/O implementations for block devices and iomap based file systems. Signed-off-by:
Kent Overstreet <kent.overstreet@gmail.com> [hch: ported to the iov_iter interface, renamed and added comments. All blame should be directed to me and all fame should go to Kent after this!] Signed-off-by:
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Jens Axboe authored
If we're doing background type writes, then use the appropriate background write flags for that. Signed-off-by:
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Jens Axboe authored
Add wbc_to_write_flags(), which returns the write modifier flags to use, based on a struct writeback_control. No functional changes in this patch, but it prepares us for factoring other wbc fields for write type. Signed-off-by:
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Jens Axboe authored
This adds a new request flag, REQ_BACKGROUND, that callers can use to tell the block layer that this is background (non-urgent) IO. Signed-off-by:
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- 01 Nov, 2016 6 commits
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Christoph Hellwig authored
Now that we have a separate header for struct bio_vec there is absolutely no excuse for including this header from non-block I/O code. Signed-off-by:
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Christoph Hellwig authored
It's only needed for the CONFIG_SWAP-only use of bio_end_io_t. Because CONFIG_SWAP implies CONFIG_BLOCK this will allow to drop some ifdefs in blk_types.h. Instead we'll need to add a few explicit includes that were implicit before, though. Signed-off-by:
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Christoph Hellwig authored
The file only needs the struct bvec_iter delcaration, which is available from bvec.h. Signed-off-by:
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Christoph Hellwig authored
No need for it - we only use struct bio_vec in prototypes and already have forward declarations for it. Signed-off-by:
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Christoph Hellwig authored
Nothing in fs.h should require blk_types.h to be included. Signed-off-by:
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Christoph Hellwig authored
This is where all the other bio operations live, so users must include bio.h anyway. Signed-off-by:
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