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authorMing Lei <ming.lei@canonical.com>2014-09-25 19:23:47 +0400
committerJens Axboe <axboe@fb.com>2014-09-26 01:22:45 +0400
commitf70ced09170761acb69840cafaace4abc72cba4b (patch)
treebc62f5926a5e8b74be30316196a41b25ece12368 /include/linux/blk-mq.h
parente97c293cdf77263abdc021de280516e0017afc84 (diff)
downloadlinux-f70ced09170761acb69840cafaace4abc72cba4b.tar.xz
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>
Diffstat (limited to 'include/linux/blk-mq.h')
-rw-r--r--include/linux/blk-mq.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 325349559fb0..02c5d950f444 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -4,6 +4,7 @@
#include <linux/blkdev.h>
struct blk_mq_tags;
+struct blk_flush_queue;
struct blk_mq_cpu_notifier {
struct list_head list;
@@ -34,6 +35,7 @@ struct blk_mq_hw_ctx {
struct request_queue *queue;
unsigned int queue_num;
+ struct blk_flush_queue *fq;
void *driver_data;
@@ -119,6 +121,10 @@ struct blk_mq_ops {
/*
* Called for every command allocated by the block layer to allow
* the driver to set up driver specific data.
+ *
+ * Tag greater than or equal to queue_depth is for setting up
+ * flush request.
+ *
* Ditto for exit/teardown.
*/
init_request_fn *init_request;