f70ced09170761acb69840cafaace4abc72cba4b |
|
25-Sep-2014 |
Ming Lei <ming.lei@canonical.com> |
blk-mq: support per-distpatch_queue flush machinery 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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17497acbdce9506fd6a75115dee4ab80c3cc5ee5 |
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24-Sep-2014 |
Tejun Heo <tj@kernel.org> |
blk-mq, percpu_ref: start q->mq_usage_counter in atomic mode 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 0a30288da1ae ("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 9eca80461a45 ("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: Tejun Heo <tj@kernel.org> Reported-by: Christoph Hellwig <hch@infradead.org> Link: http://lkml.kernel.org/g/20140919113815.GA10791@lst.de Fixes: add703fda981 ("blk-mq: use percpu_ref for mq usage count") Reviewed-by: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org>
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0152fb6b57c4fae769ee75ea2ae670f4ff39fba9 |
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14-Sep-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: pass a reserved argument to the timeout handler 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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81481eb423c295c5480a3fab9bb961cf286c91e7 |
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14-Sep-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: fix and simplify tag iteration for the timeout handler 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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c8a446ad695ada43a885ec12b38411dbd190a11b |
|
14-Sep-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: rename blk_mq_end_io to blk_mq_end_request 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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e2490073cd7c3d6f6ef6e029a208edd4d38efac4 |
|
14-Sep-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: call blk_mq_start_request from ->queue_rq 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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bf57229745f849e500ba69ff91e35bc8160a7373 |
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14-Sep-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: remove REQ_END 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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8a58d1f1f373238cb0d6d7f8d3dd723aa164b8ac |
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15-Aug-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: get rid of unused BLK_MQ_F_SHOULD_SORT flag We used to use this for determining whether to sort the dispatch list, but it's unused now. Signed-off-by: Jens Axboe <axboe@fb.com>
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8537b12034cf1fd3fab3da2c859d71f76846fae9 |
|
18-Jun-2014 |
Alexander Gordeev <agordeev@redhat.com> |
blk-mq: bitmap tag: fix races on shared ::wake_index fields 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: Alexander Gordeev <agordeev@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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a4391c6465d9c978fd4bded12e34bdde3f5458f0 |
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05-Jun-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: bump max tag depth to 10K tags 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: Jens Axboe <axboe@fb.com>
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0e62f51f8753b048f391ee2d7f2af1f7297b0be5 |
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04-Jun-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: let blk_mq_tag_to_rq() take blk_mq_tags as the main parameter 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: Jens Axboe <axboe@fb.com>
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67aec14ce87fe25bdfff7dbf468556333df11c4e |
|
30-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: make the sysfs mq/ layout reflect current mappings 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: Jens Axboe <axboe@fb.com>
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2230237500821aedfcf2bba2a79d9cbca389233c |
|
30-May-2014 |
Shaohua Li <shli@kernel.org> |
blk-mq: blk_mq_tag_to_rq should handle flush request 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: Shaohua Li <shli@fusionio.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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05f1dd5315217398fc8d122bdee80f96a9f21274 |
|
29-May-2014 |
Jens Axboe <axboe@fb.com> |
block: add queue flag for disabling SG merging 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: Jens Axboe <axboe@fb.com>
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cdef54dd85ad66e77262ea57796a3e81683dd5d6 |
|
28-May-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: remove alloc_hctx and free_hctx methods 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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4ce01dd1a07d9cf3eaf44fbf4ea9a61b11badccc |
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27-May-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: merge blk_mq_alloc_reserved_request into blk_mq_alloc_request Instead of having two almost identical copies of the same code just let the callers pass in the reserved flag directly. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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6fca6a611c27f1f0d90fbe1cc3c229dbf8c09e48 |
|
28-May-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add helper to insert requests from irq context 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: Christoph Hellwig <hch@lst.de> Reported-by: Ming Lei <tom.leiming@gmail.com> Tested-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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7738dac4f697ffbd0ed4c4aeb69a714ef9d876da |
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28-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: remove stale comment for blk_mq_complete_request() It works for both IPI and local completions as of commit 95f096849932. Signed-off-by: Jens Axboe <axboe@fb.com>
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95f096849932fe5eaa7bfec887530cf556744a76 |
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28-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: allow non-softirq completions 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: Jens Axboe <axboe@fb.com>
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f14bbe77a96bb979dc539d8308ee18a9363a544f |
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27-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: pass in suggested NUMA node to ->alloc_hctx() 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: Jens Axboe <axboe@fb.com>
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edf866b3805c5651bf7d035b72dc0190cb6ff4a7 |
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23-May-2014 |
Sam Bradshaw <sbradshaw@micron.com> |
blk-mq: export blk_mq_tag_busy_iter 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: Sam Bradshaw <sbradshaw@micron.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@fb.com>
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e814e71ba4a6e1d7509b0f4b1928365ea650cace |
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21-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: allow the hctx cpu hotplug notifier to return errors Prepare this for the next patch which adds more smarts in the plugging logic, so that we can save some memory. Signed-off-by: Jens Axboe <axboe@fb.com>
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e3a2b3f931f59d5284abd13faf8bded726884ffd |
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20-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: allow changing of queue depth through sysfs 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: Jens Axboe <axboe@fb.com>
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1429d7c9467e1e3de0b0ff91d7e4d67c1a92f8a3 |
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19-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: switch ctx pending map to the sparser blk_align_bitmap 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: Jens Axboe <axboe@fb.com>
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0d2602ca30e410e84e8bdf05c84ed5688e0a5a44 |
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13-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: improve support for shared tags maps 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: Jens Axboe <axboe@fb.com>
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4bb659b156996f2993dc16fad71fec9ee070153c |
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09-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: implement new and more efficient tagging scheme 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: Jens Axboe <axboe@fb.com>
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506e931f92defdc60c1dc4aa2ff4a19a5dcd8618 |
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07-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: add basic round-robin of what CPU to queue workqueue work on 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: Jens Axboe <axboe@fb.com>
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38535201633077cbaf8b32886b5e3005b36c9024 |
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25-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: respect rq_affinity 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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ed0791b2f83cec4e77d88c4e9baabcebf9254a78 |
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16-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add blk_mq_requeue_request 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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2f268556567ebeb3538f99b9bdad177581439dcb |
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16-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add blk_mq_start_hw_queues 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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70f4db639c5b2479e08657392cbf3ba3cceea11c |
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16-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add blk_mq_delay_queue 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: Christoph Hellwig <hch@lst.de> Modified by me to kill the unnecessary preempt disable/enable in the delayed workqueue handler. Signed-off-by: Jens Axboe <axboe@fb.com>
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1b4a325858f695a9b5041313602d34b36f463724 |
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16-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add async parameter to blk_mq_start_stopped_hw_queues Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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63151a449ebaef062ffac5b302206565ff5ef62e |
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16-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: allow drivers to hook into I/O completion 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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24d2f90309b23f2cfe016b2aebc5f0d6e01c57fd |
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15-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: split out tag initialization, support shared tags 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: Christoph Hellwig <hch@lst.de> Modular export of blk_mq_{alloc,free}_tagset added by me. Signed-off-by: Jens Axboe <axboe@fb.com>
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e9b267d91f6ddbc694cb40aa962b0b2cec03971d |
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15-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add ->init_request and ->exit_request methods 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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e4043dcf30811f5db15181168e2aac172514302a |
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09-Apr-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: ensure that hardware queues are always run on the mapped CPUs 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: Jens Axboe <axboe@fb.com>
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eeabc850b79336575da7be3dbe186a2da4de8293 |
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21-Mar-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: merge blk_mq_insert_request and blk_mq_run_request 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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5d12f905cc50c0810628d0deedd478ec2db48659 |
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19-Mar-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: fix wrong usage of hctx->state vs hctx->flags 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: Jens Axboe <axboe@fb.com>
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95363efde193079541cb379eb47140e9c4d355d5 |
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14-Mar-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: allow blk_mq_init_commands() to return failure 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: Jens Axboe <axboe@fb.com>
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d6a25b31315327eef7785b895c354cc45c3f3742 |
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21-Feb-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: support partial I/O completions 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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feb71dae1f9e0aeb056f7f639a21e620d327fc66 |
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21-Feb-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: merge blk_mq_insert_request and blk_mq_run_request 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: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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18741986a4b1dc4b1f171634c4191abc3b0fa023 |
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10-Feb-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: rework flush sequencing logic Witch to using a preallocated flush_rq for blk-mq similar to what's done with the old request path. This allows us to set up the request properly with a tag from the actually allowed range and ->rq_disk as needed by some drivers. To make life easier we also switch to dynamic allocation of ->flush_rq for the old path. This effectively reverts most of "blk-mq: fix for flush deadlock" and "blk-mq: Don't reserve a tag for flush request" Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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30a91cb4ef385fe1b260df204ef314d86fff2850 |
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10-Feb-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: rework I/O completions Rework I/O completions to work more like the old code path. blk_mq_end_io now stays out of the business of deferring completions to others CPUs and calling blk_mark_rq_complete. The latter is very important to allow completing requests that have timed out and thus are already marked completed, the former allows using the IPI callout even for driver specific completions instead of having to reimplement them. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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72a0a36e2854a6eadb4cf2561858f613f9cd4639 |
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07-Feb-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: support at_head inserations for blk_execute_rq This is neede for proper SG_IO operation as well as various uses of blk_execute_rq from the SCSI midlayer. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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f0276924fa35a3607920a58cf5d878212824b951 |
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31-Dec-2013 |
Shaohua Li <shli@kernel.org> |
blk-mq: Don't reserve a tag for flush request Reserving a tag (request) for flush to avoid dead lock is a overkill. A tag is valuable resource. We can track the number of flush requests and disallow having too many pending flush requests allocated. With this patch, blk_mq_alloc_request_pinned() could do a busy nop (but not a dead loop) if too many pending requests are allocated and new flush request is allocated. But this should not be a problem, too many pending flush requests are very rare case. I verified this can fix the deadlock caused by too many pending flush requests. Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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0d0b7d427987f6e98b6f32e84ee071f36f85c3d4 |
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28-Jan-2014 |
Jose Alonso <joalonsof@gmail.com> |
blk-mq: for_each_* macro correctness I observed that there are for_each macros that do an extra memory access beyond the defined area. Normally this does not cause problems. But, this can cause exceptions. For example: if the area is allocated at the end of a page and the next page is not accessible. For correctness, I suggest changing the arguments of the 'for loop' like others 'for_each' do in the kernel. Signed-off-by: Jose Alonso <joalonsof@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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3edcc0ce85c59d45d6dfc6a36a6b3f8b31ba9887 |
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26-Dec-2013 |
Ming Lei <tom.leiming@gmail.com> |
block: blk-mq: don't export blk_mq_free_queue() blk_mq_free_queue() is called from release handler of queue kobject, so it needn't be called from drivers. Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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3228f48be2d19b2dd90db96ec16a40187a2946f3 |
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28-Oct-2013 |
Christoph Hellwig <hch@lst.de> |
blk-mq: fix for flush deadlock The flush state machine takes in a struct request, which then is submitted multiple times to the underling driver. The old block code requeses the same request for each of those, so it does not have an issue with tapping into the request pool. The new one on the other hand allocates a new request for each of the actualy steps of the flush sequence. If have already allocated all of the tags for IO, we will fail allocating the flush request. Set aside a reserved request just for flushes. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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280d45f6c35d8d7a0fe20c36caf426e3ac139cf9 |
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25-Oct-2013 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add blk_mq_stop_hw_queues Add a helper to iterate over all hw queues and stop them. This is useful for driver that implement PM suspend functionality. Signed-off-by: Christoph Hellwig <hch@lst.de> Modified to just call blk_mq_stop_hw_queue() by Jens. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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320ae51feed5c2f13664aa05a76bec198967e04d |
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24-Oct-2013 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: new multi-queue block IO queueing mechanism Linux currently has two models for block devices: - The classic request_fn based approach, where drivers use struct request units for IO. The block layer provides various helper functionalities to let drivers share code, things like tag management, timeout handling, queueing, etc. - The "stacked" approach, where a driver squeezes in between the block layer and IO submitter. Since this bypasses the IO stack, driver generally have to manage everything themselves. With drivers being written for new high IOPS devices, the classic request_fn based driver doesn't work well enough. The design dates back to when both SMP and high IOPS was rare. It has problems with scaling to bigger machines, and runs into scaling issues even on smaller machines when you have IOPS in the hundreds of thousands per device. The stacked approach is then most often selected as the model for the driver. But this means that everybody has to re-invent everything, and along with that we get all the problems again that the shared approach solved. This commit introduces blk-mq, block multi queue support. The design is centered around per-cpu queues for queueing IO, which then funnel down into x number of hardware submission queues. We might have a 1:1 mapping between the two, or it might be an N:M mapping. That all depends on what the hardware supports. blk-mq provides various helper functions, which include: - Scalable support for request tagging. Most devices need to be able to uniquely identify a request both in the driver and to the hardware. The tagging uses per-cpu caches for freed tags, to enable cache hot reuse. - Timeout handling without tracking request on a per-device basis. Basically the driver should be able to get a notification, if a request happens to fail. - Optional support for non 1:1 mappings between issue and submission queues. blk-mq can redirect IO completions to the desired location. - Support for per-request payloads. Drivers almost always need to associate a request structure with some driver private command structure. Drivers can tell blk-mq this at init time, and then any request handed to the driver will have the required size of memory associated with it. - Support for merging of IO, and plugging. The stacked model gets neither of these. Even for high IOPS devices, merging sequential IO reduces per-command overhead and thus increases bandwidth. For now, this is provided as a potential 3rd queueing model, with the hope being that, as it matures, it can replace both the classic and stacked model. That would get us back to having just 1 real model for block devices, leaving the stacked approach to dm/md devices (as it was originally intended). Contributions in this patch from the following people: Shaohua Li <shli@fusionio.com> Alexander Gordeev <agordeev@redhat.com> Christoph Hellwig <hch@infradead.org> Mike Christie <michaelc@cs.wisc.edu> Matias Bjorling <m@bjorling.me> Jeff Moyer <jmoyer@redhat.com> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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