From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 25 Sep 2020 12:35:12 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20200925113512.GH2873@work-vm> References: <20200918213436.GA3520@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Virtio-fs] tools/virtiofs: Multi threading seems to hurt performance List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Chirantan Ekbote Cc: virtio-fs-list , qemu-devel@nongnu.org, Vivek Goyal * Chirantan Ekbote (chirantan@chromium.org) wrote: > On Sat, Sep 19, 2020 at 6:36 AM Vivek Goyal 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). > > > > FWIW, we've observed the same behavior in crosvm. Using a thread pool > for the virtiofs server consistently gave us worse performance than > using a single thread. Interesting; so it's not just us doing something silly! It does feel like you *should* be able to get some benefit from multiple threads; so I guess some more investigation needed at some time. Dave > Chirantan > > _______________________________________________ > Virtio-fs mailing list > Virtio-fs@redhat.com > https://www.redhat.com/mailman/listinfo/virtio-fs -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK