- 26 9月, 2014 1 次提交
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由 Ming Lei 提交于
This patch supports to run one single flush machinery for each blk-mq dispatch queue, so that: - current init_request and exit_request callbacks can cover flush request too, then the buggy copying way of initializing flush request's pdu can be fixed - flushing performance gets improved in case of multi hw-queue In fio sync write test over virtio-blk(4 hw queues, ioengine=sync, iodepth=64, numjobs=4, bs=4K), it is observed that througput gets increased a lot over my test environment: - throughput: +70% in case of virtio-blk over null_blk - throughput: +30% in case of virtio-blk over SSD image The multi virtqueue feature isn't merged to QEMU yet, and patches for the feature can be found in below tree: git://kernel.ubuntu.com/ming/qemu.git v2.1.0-mq.4 And simply passing 'num_queues=4 vectors=5' should be enough to enable multi queue(quad queue) feature for QEMU virtio-blk. Suggested-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 25 9月, 2014 1 次提交
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由 Tejun Heo 提交于
blk-mq uses percpu_ref for its usage counter which tracks the number of in-flight commands and used to synchronously drain the queue on freeze. percpu_ref shutdown takes measureable wallclock time as it involves a sched RCU grace period. This means that draining a blk-mq takes measureable wallclock time. One would think that this shouldn't matter as queue shutdown should be a rare event which takes place asynchronously w.r.t. userland. Unfortunately, SCSI probing involves synchronously setting up and then tearing down a lot of request_queues back-to-back for non-existent LUNs. This means that SCSI probing may take above ten seconds when scsi-mq is used. [ 0.949892] scsi host0: Virtio SCSI HBA [ 1.007864] scsi 0:0:0:0: Direct-Access QEMU QEMU HARDDISK 1.1. PQ: 0 ANSI: 5 [ 1.021299] scsi 0:0:1:0: Direct-Access QEMU QEMU HARDDISK 1.1. PQ: 0 ANSI: 5 [ 1.520356] tsc: Refined TSC clocksource calibration: 2491.910 MHz <stall> [ 16.186549] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 16.190478] sd 0:0:1:0: Attached scsi generic sg1 type 0 [ 16.194099] osd: LOADED open-osd 0.2.1 [ 16.203202] sd 0:0:0:0: [sda] 31457280 512-byte logical blocks: (16.1 GB/15.0 GiB) [ 16.208478] sd 0:0:0:0: [sda] Write Protect is off [ 16.211439] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 16.218771] sd 0:0:1:0: [sdb] 31457280 512-byte logical blocks: (16.1 GB/15.0 GiB) [ 16.223264] sd 0:0:1:0: [sdb] Write Protect is off [ 16.225682] sd 0:0:1:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA This is also the reason why request_queues start in bypass mode which is ended on blk_register_queue() as shutting down a fully functional queue also involves a RCU grace period and the queues for non-existent SCSI devices never reach registration. blk-mq basically needs to do the same thing - start the mq in a degraded mode which is faster to shut down and then make it fully functional only after the queue reaches registration. percpu_ref recently grew facilities to force atomic operation until explicitly switched to percpu mode, which can be used for this purpose. This patch makes blk-mq initialize q->mq_usage_counter in atomic mode and switch it to percpu mode only once blk_register_queue() is reached. Note that this issue was previously worked around by 0a30288d ("blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe") for v3.17. The temp fix was reverted in preparation of adding persistent atomic mode to percpu_ref by 9eca8046 ("Revert "blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe""). This patch and the prerequisite percpu_ref changes will be merged during v3.18 devel cycle. Signed-off-by: NTejun Heo <tj@kernel.org> Reported-by: NChristoph Hellwig <hch@infradead.org> Link: http://lkml.kernel.org/g/20140919113815.GA10791@lst.de Fixes: add703fd ("blk-mq: use percpu_ref for mq usage count") Reviewed-by: NKent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org>
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- 23 9月, 2014 5 次提交
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由 Christoph Hellwig 提交于
Allow blk-mq to pass an argument to the timeout handler to indicate if we're timing out a reserved or regular command. For many drivers those need to be handled different. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Don't do a kmalloc from timer to handle timeouts, chances are we could be under heavy load or similar and thus just miss out on the timeouts. Fortunately it is very easy to just iterate over all in use tags, and doing this properly actually cleans up the blk_mq_busy_iter API as well, and prepares us for the next patch by passing a reserved argument to the iterator. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Now that we've changed the driver API on the submission side use the opportunity to fix up the name on the completion side to fit into the general scheme. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
When we call blk_mq_start_request from the core blk-mq code before calling into ->queue_rq there is a racy window where the timeout handler can hit before we've fully set up the driver specific part of the command. Move the call to blk_mq_start_request into the driver so the driver can start the request only once it is fully set up. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Pass an explicit parameter for the last request in a batch to ->queue_rq instead of using a request flag. Besides being a cleaner and non-stateful interface this is also required for the next patch, which fixes the blk-mq I/O submission code to not start a time too early. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 16 8月, 2014 1 次提交
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由 Jens Axboe 提交于
We used to use this for determining whether to sort the dispatch list, but it's unused now. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 18 6月, 2014 1 次提交
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由 Alexander Gordeev 提交于
Fix racy updates of shared blk_mq_bitmap_tags::wake_index and blk_mq_hw_ctx::wake_index fields. Cc: Ming Lei <tom.leiming@gmail.com> Signed-off-by: NAlexander Gordeev <agordeev@redhat.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 06 6月, 2014 1 次提交
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由 Jens Axboe 提交于
For some scsi-mq cases, the tag map can be huge. So increase the max number of tags we support. Additionally, don't fail with EINVAL if a user requests too many tags. Warn that the tag depth has been adjusted down, and store the new value inside the tag_set passed in. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 05 6月, 2014 1 次提交
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由 Jens Axboe 提交于
We currently pass in the hardware queue, and get the tags from there. But from scsi-mq, with a shared tag space, it's a lot more convenient to pass in the blk_mq_tags instead as the hardware queue isn't always directly available. So instead of having to re-map to a given hardware queue from rq->mq_ctx, just pass in the tags structure. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 30 5月, 2014 2 次提交
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由 Jens Axboe 提交于
Currently blk-mq registers all the hardware queues in sysfs, regardless of whether it uses them (e.g. they have CPU mappings) or not. The unused hardware queues lack the cpux/ directories, and the other sysfs entries (like active, pending, etc) are all zeroes. Change this so that sysfs correctly reflects the current mappings of the hardware queues. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Shaohua Li 提交于
flush request is special, which borrows the tag from the parent request. Hence blk_mq_tag_to_rq needs special handling to return the flush request from the tag. Signed-off-by: NShaohua Li <shli@fusionio.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 29 5月, 2014 2 次提交
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由 Jens Axboe 提交于
If devices are not SG starved, we waste a lot of time potentially collapsing SG segments. Enough that 1.5% of the CPU time goes to this, at only 400K IOPS. Add a queue flag, QUEUE_FLAG_NO_SG_MERGE, which just returns the number of vectors in a bio instead of looping over all segments and checking for collapsible ones. Add a BLK_MQ_F_SG_MERGE flag so that drivers can opt-in on the sg merging, if they so desire. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
There is no need for drivers to control hardware context allocation now that we do the context to node mapping in common code. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 28 5月, 2014 5 次提交
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由 Christoph Hellwig 提交于
Instead of having two almost identical copies of the same code just let the callers pass in the reserved flag directly. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Both the cache flush state machine and the SCSI midlayer want to submit requests from irq context, and the current per-request requeue_work unfortunately causes corruption due to sharing with the csd field for flushes. Replace them with a per-request_queue list of requests to be requeued. Based on an earlier test by Ming Lei. Signed-off-by: NChristoph Hellwig <hch@lst.de> Reported-by: NMing Lei <tom.leiming@gmail.com> Tested-by: NMing Lei <tom.leiming@gmail.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
It works for both IPI and local completions as of commit 95f09684. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
Right now we export two ways of completing a request: 1) blk_mq_complete_request(). This uses an IPI (if needed) and completes through q->softirq_done_fn(). It also works with timeouts. 2) blk_mq_end_io(). This completes inline, and ignores any timeout state of the request. Let blk_mq_complete_request() handle non-softirq_done_fn completions as well, by just completing inline. If a driver has enough completion ports to place completions correctly, it need not define a mq_ops->complete() and we can avoid an indirect function call by doing the completion inline. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
Drivers currently have to figure this out on their own, and they are missing information to do it properly. The ones that did attempt to do it, do it wrong. So just pass in the suggested node directly to the alloc function. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 24 5月, 2014 1 次提交
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由 Sam Bradshaw 提交于
Export the blk-mq in-flight tag iterator for driver consumption. This is particularly useful in exception paths or SRSI where in-flight IOs need to be cancelled and/or reissued. The NVMe driver conversion will use this. Signed-off-by: NSam Bradshaw <sbradshaw@micron.com> Signed-off-by: NMatias Bjørling <m@bjorling.me> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 22 5月, 2014 1 次提交
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由 Jens Axboe 提交于
Prepare this for the next patch which adds more smarts in the plugging logic, so that we can save some memory. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 21 5月, 2014 1 次提交
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由 Jens Axboe 提交于
For request_fn based devices, the block layer exports a 'nr_requests' file through sysfs to allow adjusting of queue depth on the fly. Currently this returns -EINVAL for blk-mq, since it's not wired up. Wire this up for blk-mq, so that it now also always dynamic adjustments of the allowed queue depth for any given block device managed by blk-mq. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 20 5月, 2014 1 次提交
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由 Jens Axboe 提交于
Each hardware queue has a bitmap of software queues with pending requests. When new IO is queued on a software queue, the bit is set, and when IO is pruned on a hardware queue run, the bit is cleared. This causes a lot of traffic. Switch this from the regular BITS_PER_LONG bitmap to a sparser layout, similarly to what was done for blk-mq tagging. 20% performance increase was observed for single threaded IO, and about 15% performanc increase on multiple threads driving the same device. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 14 5月, 2014 1 次提交
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由 Jens Axboe 提交于
This adds support for active queue tracking, meaning that the blk-mq tagging maintains a count of active users of a tag set. This allows us to maintain a notion of fairness between users, so that we can distribute the tag depth evenly without starving some users while allowing others to try unfair deep queues. If sharing of a tag set is detected, each hardware queue will track the depth of its own queue. And if this exceeds the total depth divided by the number of active queues, the user is actively throttled down. The active queue count is done lazily to avoid bouncing that data between submitter and completer. Each hardware queue gets marked active when it allocates its first tag, and gets marked inactive when 1) the last tag is cleared, and 2) the queue timeout grace period has passed. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 09 5月, 2014 1 次提交
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由 Jens Axboe 提交于
blk-mq currently uses percpu_ida for tag allocation. But that only works well if the ratio between tag space and number of CPUs is sufficiently high. For most devices and systems, that is not the case. The end result if that we either only utilize the tag space partially, or we end up attempting to fully exhaust it and run into lots of lock contention with stealing between CPUs. This is not optimal. This new tagging scheme is a hybrid bitmap allocator. It uses two tricks to both be SMP friendly and allow full exhaustion of the space: 1) We cache the last allocated (or freed) tag on a per blk-mq software context basis. This allows us to limit the space we have to search. The key element here is not caching it in the shared tag structure, otherwise we end up dirtying more shared cache lines on each allocate/free operation. 2) The tag space is split into cache line sized groups, and each context will start off randomly in that space. Even up to full utilization of the space, this divides the tag users efficiently into cache line groups, avoiding dirtying the same one both between allocators and between allocator and freeer. This scheme shows drastically better behaviour, both on small tag spaces but on large ones as well. It has been tested extensively to show better performance for all the cases blk-mq cares about. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 08 5月, 2014 1 次提交
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由 Jens Axboe 提交于
Right now we just pick the first CPU in the mask, but that can easily overload that one. Add some basic batching and round-robin all the entries in the mask instead. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 25 4月, 2014 1 次提交
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由 Christoph Hellwig 提交于
The blk-mq code is using it's own version of the I/O completion affinity tunables, which causes a few issues: - the rq_affinity sysfs file doesn't work for blk-mq devices, even if it still is present, thus breaking existing tuning setups. - the rq_affinity = 1 mode, which is the defauly for legacy request based drivers isn't implemented at all. - blk-mq drivers don't implement any completion affinity with the default flag settings. This patches removes the blk-mq ipi_redirect flag and sysfs file, as well as the internal BLK_MQ_F_SHOULD_IPI flag and replaces it with code that respects the queue-wide rq_affinity flags and also implements the rq_affinity = 1 mode. This means I/O completion affinity can now only be tuned block-queue wide instead of per context, which seems more sensible to me anyway. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 17 4月, 2014 5 次提交
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由 Christoph Hellwig 提交于
This allows to requeue a request that has been accepted by ->queue_rq earlier. This is needed by the SCSI layer in various error conditions. The existing internal blk_mq_requeue_request is renamed to __blk_mq_requeue_request as it is a lower level building block for this funtionality. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Add a helper to unconditionally kick contexts of a queue. This will be needed by the SCSI layer to provide fair queueing between multiple devices on a single host. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Add a blk-mq equivalent to blk_delay_queue so that the scsi layer can ask to be kicked again after a delay. Signed-off-by: NChristoph Hellwig <hch@lst.de> Modified by me to kill the unnecessary preempt disable/enable in the delayed workqueue handler. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Split out the bottom half of blk_mq_end_io so that drivers can perform work when they know a request has been completed, but before it has been freed. This also obsoletes blk_mq_end_io_partial as drivers can now pass any value to blk_update_request directly. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 16 4月, 2014 2 次提交
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由 Christoph Hellwig 提交于
Add a new blk_mq_tag_set structure that gets set up before we initialize the queue. A single blk_mq_tag_set structure can be shared by multiple queues. Signed-off-by: NChristoph Hellwig <hch@lst.de> Modular export of blk_mq_{alloc,free}_tagset added by me. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
The current blk_mq_init_commands/blk_mq_free_commands interface has a two problems: 1) Because only the constructor is passed to blk_mq_init_commands there is no easy way to clean up when a comman initialization failed. The current code simply leaks the allocations done in the constructor. 2) There is no good place to call blk_mq_free_commands: before blk_cleanup_queue there is no guarantee that all outstanding commands have completed, so we can't free them yet. After blk_cleanup_queue the queue has usually been freed. This can be worked around by grabbing an unconditional reference before calling blk_cleanup_queue and dropping it after blk_mq_free_commands is done, although that's not exatly pretty and driver writers are guaranteed to get it wrong sooner or later. Both issues are easily fixed by making the request constructor and destructor normal blk_mq_ops methods. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 10 4月, 2014 1 次提交
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由 Jens Axboe 提交于
Instead of providing soft mappings with no guarantees on hardware queues always being run on the right CPU, switch to a hard mapping guarantee that ensure that we always run the hardware queue on (one of, if more) the mapped CPU. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 21 3月, 2014 1 次提交
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由 Christoph Hellwig 提交于
It's almost identical to blk_mq_insert_request, so fold the two into one slightly more generic function by making the flush special case a bit smarted. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 20 3月, 2014 1 次提交
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由 Jens Axboe 提交于
BLK_MQ_F_* flags are for hctx->flags, and are non-atomic and set at registration time. BLK_MQ_S_* flags are dynamic and atomic, and are accessed through hctx->state. Some of the BLK_MQ_S_STOPPED uses were wrong. Additionally, the header file should not use a bit shift for the _S_ flags, as they are done through the set/test_bit functions. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 15 3月, 2014 1 次提交
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由 Jens Axboe 提交于
If drivers do dynamic allocation in the hardware command init path, then we need to be able to handle and return failures. And if they do allocations or mappings in the init command path, then we need a cleanup function to free up that space at exit time. So add blk_mq_free_commands() as the cleanup function. This is required for the mtip32xx driver conversion to blk-mq. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 22 2月, 2014 1 次提交
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由 Christoph Hellwig 提交于
Add a new blk_mq_end_io_partial function to partially complete requests as needed by the SCSI layer. We do this by reusing blk_update_request to advance the bio instead of having a simplified version of it in the blk-mq code. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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