On Tue, 16 May 2023 at 20:28, David Wysochanski <dwysocha@xxxxxxxxxx> wrote: > > On Tue, May 16, 2023 at 11:42 AM Chris Chilvers <chilversc@xxxxxxxxx> wrote: > > > > While testing the fscache performance fixes [1] that were merged into 6.4-rc1 > > it appears that the caching no longer works. The client will write to the cache > > but never reads. > > > Thanks for the report. > > If you reboot do you see reads from the cache? On the first read after a reboot it uses the cache, but subsequent reads do not use the cache. > You can check if the cache is being read from by looking in > /proc/fs/fscache/stats > at the "IO" line: > # grep IO /proc/fs/fscache/stats > IO : rd=80030 wr=0 Running the tests 4 times (twice before reboot, and twice after) give the following metrics: FS-Cache I/O (delta) Run rd wr 1 0 39,250 2 130 38,894 3 39,000 0 4 72 38,991 > Can you share: > 1. NFS server you're using (is it localhost or something else) > 2. NFS version The NFS server and client are separate VMs on the same network. Server NFS version: Ubuntu 22.04 jammy, kernel 5.15.0-1021-gcp Client NFS version: Ubuntu 22.04 jammy, kernel 6.4.0-060400rc1-generic (https://kernel.ubuntu.com/~kernel-ppa/mainline/v6.4-rc1/) Client nfs-utils: 2.6.3-rc6 Client cachefilesd: 0.10.10-0.2ubuntu1 > In addition to checking the above for the reads from the cache, you can also > see whether NFS reads are going over the wire pretty easily with a similar > technique. > > Copy /proc/self/mounstats to a file before your test, then make a second copy > after the test, then run mountstats as follows: > mountstats -S /tmp/mountstats.1 -f /tmp/mountstats.2 app read = applications read bytes via read(2) client read = client read bytes via NFS READ Run app read client read 1 322,122,547,200 322,122,547,200 2 322,122,547,200 321,048,805,376 3 322,122,547,200 0 4 322,122,547,200 321,593,053,184 I've put the full data in a GitHub gist, along with a graph collected from a metrics agent: https://gist.github.com/chilversc/54eb76155ad37b66cb85186e7449beaa https://gist.githubusercontent.com/chilversc/54eb76155ad37b66cb85186e7449beaa/raw/09828c596d0cfc44bc0eb67f40e4033db202326e/metrics.png -- Linux-cachefs mailing list Linux-cachefs@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/linux-cachefs
