Re: tools/virtiofs: Multi threading seems to hurt performance

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Vivek Goyal (vgoyal@redhat.com) wrote:
> Hi All,
> 
> virtiofsd default thread pool size is 64. To me it feels that in most of
> the cases thread pool size 1 performs better than thread pool size 64.
> 
> I ran virtiofs-tests.
> 
> https://github.com/rhvgoyal/virtiofs-tests
> 
> And here are the comparision results. To me it seems that by default
> we should switch to 1 thread (Till we can figure out how to make
> multi thread performance better even when single process is doing
> I/O in client).
> 
> I am especially more interested in getting performance better for
> single process in client. If that suffers, then it is pretty bad.
> 
> Especially look at randread, randwrite, seqwrite performance. seqread
> seems pretty good anyway.
> 
> If I don't run who test suite and just ran randread-psync job,
> my throughput jumps from around 40MB/s to 60MB/s. That's a huge
> jump I would say.
> 
> Thoughts?

What's your host setup; how many cores has the host got and how many did
you give the guest?

Dave

> Thanks
> Vivek
> 
> 
> NAME                    WORKLOAD                Bandwidth       IOPS            
> cache-auto              seqread-psync           690(MiB/s)      172k            
> cache-auto-1-thread     seqread-psync           729(MiB/s)      182k            
> 
> cache-auto              seqread-psync-multi     2578(MiB/s)     644k            
> cache-auto-1-thread     seqread-psync-multi     2597(MiB/s)     649k            
> 
> cache-auto              seqread-mmap            660(MiB/s)      165k            
> cache-auto-1-thread     seqread-mmap            672(MiB/s)      168k            
> 
> cache-auto              seqread-mmap-multi      2499(MiB/s)     624k            
> cache-auto-1-thread     seqread-mmap-multi      2618(MiB/s)     654k            
> 
> cache-auto              seqread-libaio          286(MiB/s)      71k             
> cache-auto-1-thread     seqread-libaio          260(MiB/s)      65k             
> 
> cache-auto              seqread-libaio-multi    1508(MiB/s)     377k            
> cache-auto-1-thread     seqread-libaio-multi    986(MiB/s)      246k            
> 
> cache-auto              randread-psync          35(MiB/s)       9191            
> cache-auto-1-thread     randread-psync          55(MiB/s)       13k             
> 
> cache-auto              randread-psync-multi    179(MiB/s)      44k             
> cache-auto-1-thread     randread-psync-multi    209(MiB/s)      52k             
> 
> cache-auto              randread-mmap           32(MiB/s)       8273            
> cache-auto-1-thread     randread-mmap           50(MiB/s)       12k             
> 
> cache-auto              randread-mmap-multi     161(MiB/s)      40k             
> cache-auto-1-thread     randread-mmap-multi     185(MiB/s)      46k             
> 
> cache-auto              randread-libaio         268(MiB/s)      67k             
> cache-auto-1-thread     randread-libaio         254(MiB/s)      63k             
> 
> cache-auto              randread-libaio-multi   256(MiB/s)      64k             
> cache-auto-1-thread     randread-libaio-multi   155(MiB/s)      38k             
> 
> cache-auto              seqwrite-psync          23(MiB/s)       6026            
> cache-auto-1-thread     seqwrite-psync          30(MiB/s)       7925            
> 
> cache-auto              seqwrite-psync-multi    100(MiB/s)      25k             
> cache-auto-1-thread     seqwrite-psync-multi    154(MiB/s)      38k             
> 
> cache-auto              seqwrite-mmap           343(MiB/s)      85k             
> cache-auto-1-thread     seqwrite-mmap           355(MiB/s)      88k             
> 
> cache-auto              seqwrite-mmap-multi     408(MiB/s)      102k            
> cache-auto-1-thread     seqwrite-mmap-multi     438(MiB/s)      109k            
> 
> cache-auto              seqwrite-libaio         41(MiB/s)       10k             
> cache-auto-1-thread     seqwrite-libaio         65(MiB/s)       16k             
> 
> cache-auto              seqwrite-libaio-multi   137(MiB/s)      34k             
> cache-auto-1-thread     seqwrite-libaio-multi   214(MiB/s)      53k             
> 
> cache-auto              randwrite-psync         22(MiB/s)       5801            
> cache-auto-1-thread     randwrite-psync         30(MiB/s)       7927            
> 
> cache-auto              randwrite-psync-multi   100(MiB/s)      25k             
> cache-auto-1-thread     randwrite-psync-multi   151(MiB/s)      37k             
> 
> cache-auto              randwrite-mmap          31(MiB/s)       7984            
> cache-auto-1-thread     randwrite-mmap          55(MiB/s)       13k             
> 
> cache-auto              randwrite-mmap-multi    124(MiB/s)      31k             
> cache-auto-1-thread     randwrite-mmap-multi    213(MiB/s)      53k             
> 
> cache-auto              randwrite-libaio        40(MiB/s)       10k             
> cache-auto-1-thread     randwrite-libaio        64(MiB/s)       16k             
> 
> cache-auto              randwrite-libaio-multi  139(MiB/s)      34k             
> cache-auto-1-thread     randwrite-libaio-multi  212(MiB/s)      53k             
> 
> 
> 
> 
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK