[Virtio-fs] [PATCH v2 0/2][RFC] virtiofsd: Improve io bandwidth by replacing pwrite with pwritev

[Stefan Hajnoczi]

On Wed, Aug 07, 2019 at 02:57:05PM +0800, piaojun wrote:

Hi,
Please use git send-email --thread so that each patch is part of the
same email thread.  This makes it easier to locate the entire patch
series in an email client and to apply the patches together.

> >From my test, write bandwidth will be improved greatly by replacing
> pwrite with pwritev, and the test result as below:
> 
> ---
> pwrite:
> # fio -direct=1 -time_based -iodepth=64 -rw=randwrite -ioengine=libaio -bs=1M -size=1G -numjob=16 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
> file: (g=0): rw=randwrite, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=64
> ...
> fio-2.13
> Starting 16 processes
> Jobs: 16 (f=16): [w(16)] [100.0% done] [0KB/886.0MB/0KB /s] [0/886/0 iops] [eta 00m:00s]
> file: (groupid=0, jobs=16): err= 0: pid=5799: Tue Aug 6 18:48:26 2019
> write: io=26881MB, bw=916988KB/s, iops=895, runt= 30018msec
> 
> pwritev:
> # fio -direct=1 -time_based -iodepth=64 -rw=randwrite -ioengine=libaio -bs=1M -size=1G -numjob=16 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
> file: (g=0): rw=randwrite, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=64
> ...
> fio-2.13
> Starting 16 processes
> Jobs: 16 (f=16): [w(16)] [100.0% done] [0KB/1793MB/0KB /s] [0/1793/0 iops] [eta 00m:00s]
> file: (groupid=0, jobs=16): err= 0: pid=6328: Tue Aug 6 18:22:17 2019
> write: io=52775MB, bw=1758.7MB/s, iops=1758, runt= 30009msec

Nice performance improvement!