Re: virtiofs vs 9p performance(Re: tools/virtiofs: Multi threading seems to hurt performance)

[Dr. David Alan Gilbert]

* Christian Schoenebeck (qemu_oss@crudebyte.com) wrote:
> On Freitag, 25. September 2020 14:41:39 CEST Dr. David Alan Gilbert wrote:
> > > Hi Carlos,
> > > 
> > > So you are running following test.
> > > 
> > > fio --direct=1 --gtod_reduce=1 --name=test
> > > --filename=random_read_write.fio --bs=4k --iodepth=64 --size=4G
> > > --readwrite=randrw --rwmixread=75 --output=/output/fio.txt
> > > 
> > > And following are your results.
> > > 
> > > 9p
> > > --
> > > READ: bw=211MiB/s (222MB/s), 211MiB/s-211MiB/s (222MB/s-222MB/s),
> > > io=3070MiB (3219MB), run=14532-14532msec
> > > 
> > > WRITE: bw=70.6MiB/s (74.0MB/s), 70.6MiB/s-70.6MiB/s (74.0MB/s-74.0MB/s),
> > > io=1026MiB (1076MB), run=14532-14532msec
> > > 
> > > virtiofs
> > > --------
> > > 
> > > Run status group 0 (all jobs):
> > >    READ: bw=159MiB/s (167MB/s), 159MiB/s-159MiB/s (167MB/s-167MB/s),
> > >    io=3070MiB (3219MB), run=19321-19321msec>   
> > >   WRITE: bw=53.1MiB/s (55.7MB/s), 53.1MiB/s-53.1MiB/s (55.7MB/s-55.7MB/s),
> > >   io=1026MiB (1076MB), run=19321-19321msec> 
> > > So looks like you are getting better performance with 9p in this case.
> > 
> > That's interesting, because I've just tried similar again with my
> > ramdisk setup:
> > 
> > fio --direct=1 --gtod_reduce=1 --name=test --filename=random_read_write.fio
> > --bs=4k --iodepth=64 --size=4G --readwrite=randrw --rwmixread=75
> > --output=aname.txt
> > 
> > 
> > virtiofs default options
> > test: (g=0): rw=randrw, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T)
> > 4096B-4096B, ioengine=psync, iodepth=64 fio-3.21
> > Starting 1 process
> > test: Laying out IO file (1 file / 4096MiB)
> > 
> > test: (groupid=0, jobs=1): err= 0: pid=773: Fri Sep 25 12:28:32 2020
> >   read: IOPS=18.3k, BW=71.3MiB/s (74.8MB/s)(3070MiB/43042msec)
> >    bw (  KiB/s): min=70752, max=77280, per=100.00%, avg=73075.71,
> > stdev=1603.47, samples=85 iops        : min=17688, max=19320, avg=18268.92,
> > stdev=400.86, samples=85 write: IOPS=6102, BW=23.8MiB/s
> > (24.0MB/s)(1026MiB/43042msec); 0 zone resets bw (  KiB/s): min=23128,
> > max=25696, per=100.00%, avg=24420.40, stdev=583.08, samples=85 iops       
> > : min= 5782, max= 6424, avg=6105.09, stdev=145.76, samples=85 cpu         
> > : usr=0.10%, sys=30.09%, ctx=1245312, majf=0, minf=6 IO depths    :
> > 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit    :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete  :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued rwts:
> > total=785920,262656,0,0 short=0,0,0,0 dropped=0,0,0,0 latency   : target=0,
> > window=0, percentile=100.00%, depth=64
> > 
> > Run status group 0 (all jobs):
> >    READ: bw=71.3MiB/s (74.8MB/s), 71.3MiB/s-71.3MiB/s (74.8MB/s-74.8MB/s),
> > io=3070MiB (3219MB), run=43042-43042msec WRITE: bw=23.8MiB/s (24.0MB/s),
> > 23.8MiB/s-23.8MiB/s (24.0MB/s-24.0MB/s), io=1026MiB (1076MB),
> > run=43042-43042msec
> > 
> > virtiofs cache=none
> > test: (g=0): rw=randrw, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T)
> > 4096B-4096B, ioengine=psync, iodepth=64 fio-3.21
> > Starting 1 process
> > 
> > test: (groupid=0, jobs=1): err= 0: pid=740: Fri Sep 25 12:30:57 2020
> >   read: IOPS=22.9k, BW=89.6MiB/s (93.0MB/s)(3070MiB/34256msec)
> >    bw (  KiB/s): min=89048, max=94240, per=100.00%, avg=91871.06,
> > stdev=967.87, samples=68 iops        : min=22262, max=23560, avg=22967.76,
> > stdev=241.97, samples=68 write: IOPS=7667, BW=29.0MiB/s
> > (31.4MB/s)(1026MiB/34256msec); 0 zone resets bw (  KiB/s): min=29264,
> > max=32248, per=100.00%, avg=30700.82, stdev=541.97, samples=68 iops       
> > : min= 7316, max= 8062, avg=7675.21, stdev=135.49, samples=68 cpu         
> > : usr=1.03%, sys=27.64%, ctx=1048635, majf=0, minf=5 IO depths    :
> > 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit    :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete  :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued rwts:
> > total=785920,262656,0,0 short=0,0,0,0 dropped=0,0,0,0 latency   : target=0,
> > window=0, percentile=100.00%, depth=64
> > 
> > Run status group 0 (all jobs):
> >    READ: bw=89.6MiB/s (93.0MB/s), 89.6MiB/s-89.6MiB/s (93.0MB/s-93.0MB/s),
> > io=3070MiB (3219MB), run=34256-34256msec WRITE: bw=29.0MiB/s (31.4MB/s),
> > 29.0MiB/s-29.0MiB/s (31.4MB/s-31.4MB/s), io=1026MiB (1076MB),
> > run=34256-34256msec
> > 
> > virtiofs cache=none thread-pool-size=1
> > test: (g=0): rw=randrw, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T)
> > 4096B-4096B, ioengine=psync, iodepth=64 fio-3.21
> > Starting 1 process
> > 
> > test: (groupid=0, jobs=1): err= 0: pid=738: Fri Sep 25 12:33:17 2020
> >   read: IOPS=23.7k, BW=92.4MiB/s (96.9MB/s)(3070MiB/33215msec)
> >    bw (  KiB/s): min=89808, max=111952, per=100.00%, avg=94762.30,
> > stdev=4507.43, samples=66 iops        : min=22452, max=27988, avg=23690.58,
> > stdev=1126.86, samples=66 write: IOPS=7907, BW=30.9MiB/s
> > (32.4MB/s)(1026MiB/33215msec); 0 zone resets bw (  KiB/s): min=29424,
> > max=37112, per=100.00%, avg=31668.73, stdev=1558.69, samples=66 iops       
> > : min= 7356, max= 9278, avg=7917.18, stdev=389.67, samples=66 cpu         
> > : usr=0.43%, sys=29.07%, ctx=1048627, majf=0, minf=7 IO depths    :
> > 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit    :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete  :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued rwts:
> > total=785920,262656,0,0 short=0,0,0,0 dropped=0,0,0,0 latency   : target=0,
> > window=0, percentile=100.00%, depth=64
> > 
> > Run status group 0 (all jobs):
> >    READ: bw=92.4MiB/s (96.9MB/s), 92.4MiB/s-92.4MiB/s (96.9MB/s-96.9MB/s),
> > io=3070MiB (3219MB), run=33215-33215msec WRITE: bw=30.9MiB/s (32.4MB/s),
> > 30.9MiB/s-30.9MiB/s (32.4MB/s-32.4MB/s), io=1026MiB (1076MB),
> > run=33215-33215msec
> > 
> > 9p ( mount -t 9p -o trans=virtio kernel /mnt
> > -oversion=9p2000.L,cache=mmap,msize=1048576 ) test: (g=0): rw=randrw,
> Bottleneck ------------------------------^
> 
> By increasing 'msize' you would encounter better 9P I/O results.

OK, I thought that was bigger than the default;  what number should I
use?

Dave

> > bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=psync,
> > iodepth=64 fio-3.21
> > Starting 1 process
> > 
> > test: (groupid=0, jobs=1): err= 0: pid=736: Fri Sep 25 12:36:00 2020
> >   read: IOPS=16.2k, BW=63.5MiB/s (66.6MB/s)(3070MiB/48366msec)
> >    bw (  KiB/s): min=63426, max=82776, per=100.00%, avg=65054.28,
> > stdev=2014.88, samples=96 iops        : min=15856, max=20694, avg=16263.34,
> > stdev=503.74, samples=96 write: IOPS=5430, BW=21.2MiB/s
> > (22.2MB/s)(1026MiB/48366msec); 0 zone resets bw (  KiB/s): min=20916,
> > max=27632, per=100.00%, avg=21740.64, stdev=735.73, samples=96 iops       
> > : min= 5229, max= 6908, avg=5434.99, stdev=183.95, samples=96 cpu         
> > : usr=1.60%, sys=14.28%, ctx=1049348, majf=0, minf=7 IO depths    :
> > 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit    :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete  :
> > 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued rwts:
> > total=785920,262656,0,0 short=0,0,0,0 dropped=0,0,0,0 latency   : target=0,
> > window=0, percentile=100.00%, depth=64
> > 
> > Run status group 0 (all jobs):
> >    READ: bw=63.5MiB/s (66.6MB/s), 63.5MiB/s-63.5MiB/s (66.6MB/s-66.6MB/s),
> > io=3070MiB (3219MB), run=48366-48366msec WRITE: bw=21.2MiB/s (22.2MB/s),
> > 21.2MiB/s-21.2MiB/s (22.2MB/s-22.2MB/s), io=1026MiB (1076MB),
> > run=48366-48366msec
> > 
> > So I'm sitll beating 9p; the thread-pool-size=1 seems to be great for
> > read performance here.
> > 
> > Dave
> 
> Best regards,
> Christian Schoenebeck
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK