From: Ming Lei Date: Thu, 25 Sep 2014 15:23:47 +0000 (+0800) Subject: blk-mq: support per-distpatch_queue flush machinery X-Git-Tag: fixes-against-v3.18-rc2~51^2~27 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f70ced091707;p=pandora-kernel.git 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 Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- Reading git-diff-tree failed