diff options
| author | Stefan Hajnoczi <stefanha@redhat.com> | 2015-07-20 16:54:16 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2015-10-12 09:21:10 +0100 |
| commit | fc73548e444ae3239f6cef44a5200b5d2c3e85d1 (patch) | |
| tree | b403ecd4b4a52f4b10999d36fb78cddf5ff91a0a | |
| parent | 5ec911c30ff4337d4185e29e82a254349f5a22da (diff) | |
virtio-blk: use blk_io_plug/unplug for Linux AIO batching
The raw-posix block driver implements Linux AIO batching so multiple
requests can be submitted with a single io_submit(2) system call.
Batching is currently only used by virtio-scsi and
virtio-blk-data-plane.
Enable batching for regular virtio-blk so the number of io_submit(2)
system calls is reduced for workloads with queue depth > 1.
In 4KB random read performance tests with queue depth 32, the CPU
utilization on the host is reduced by 9.4%. The fio job is as follows:
[global]
bs=4k
ioengine=libaio
iodepth=32
direct=1
sync=0
time_based=1
runtime=30
clocksource=gettimeofday
ramp_time=5
[job1]
rw=randread
filename=/dev/vdb
size=4096M
write_bw_log=fio
write_iops_log=fio
write_lat_log=fio
log_avg_msec=1000
This benchmark was run on an raw image on LVM. The disk was an SSD
drive and -drive cache=none,aio=native was used.
Tested-by: Pradeep Surisetty <psuriset@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
| -rw-r--r-- | hw/block/virtio-blk.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index f9301ae541..76d27f9376 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -600,6 +600,8 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) return; } + blk_io_plug(s->blk); + while ((req = virtio_blk_get_request(s))) { virtio_blk_handle_request(req, &mrb); } @@ -607,6 +609,8 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) if (mrb.num_reqs) { virtio_blk_submit_multireq(s->blk, &mrb); } + + blk_io_unplug(s->blk); } static void virtio_blk_dma_restart_bh(void *opaque) |