Open Stack

On 2019/1/16 3:16, Vivek Goyal wrote:
> On Thu, Dec 27, 2018 at 10:57:21AM +0800, jiangyiwen wrote:
> 
> [..]
>>>>
>>>> 4. When I use fio with psync, write/read only 20% improve than 9p, I think
>>>> psync can be more used than mmap. This user-case may need to improved.
>>>
>>> Can you send me your fio job. I want to try it out.
>>>
>>
>> fio -filename=/mnt/virtio_fs/file -rw=read -bs=4k -size=6G -iodepth=1 -ioengine=psync -numjobs=1 -group_reporting -name=xxx -time_based -runtime=120
> 
> Ok, finally I tried this in bunch of configurations. without dax and
> cache=none, I see roughly 100% improvement.
> 
> cache=none
> ==========
> virtio-9p: 28MB/s
> virtio-fs: 59MB/s
> 
> Above is without dax enabled and libfuse daemon filters O_DIRECT flag on
> host so that file will be cached in host (despite the fact guest opened
> it with O_DIRECT). 
> 
> I then tried "cache=always" and did direct I/O from guest. This will avoid
> page cache in guest but will use page cache on host.
> 
> cache=always
> ===========
> virtio-fs: 52MB/s
> virtio-fs (dax): 175MB/s
> 
> Notice that with dax performance is alsmost 5x times better as compared to
> virtio-9p.
> 
> Following is my fio job for testing.
> 
> =======================================
> [global]
> name=fio-psync
> rw=read
> direct=1
> numjobs=1
> runtime=60
> bs=4k
> 
> [file1]
> size=6G
> ioengine=psync
> iodepth=1
> filename=fio-psync-file
> ========================================
> 
> So I think even without dax, performance improvement is significant and
> enabling dax speeds it up very significantly.
> 
> Thanks
> Vivek
> 
> .
> 

Hi Vivek,

Thank your very much, this is great.

Yiwen.