On Fri, Aug 4, 2023 at 9:31 AM Ole Salscheider <ole@xxxxxxxxxxxxxxx> wrote: > > > > On 02.08.23 17:08, David Wysochanski wrote: > > On Wed, Aug 2, 2023 at 3:35 AM Ole Salscheider <ole@xxxxxxxxxxxxxxx> wrote: > >> > >> Hello, > >> > >> I noticed some strange behaviour of fscache with kernel 6.4.x in > >> combination with NFS (v4.2) and the pagecache. > >> > >> I have multiple clients mounting an NFS v4.2 file system from a server > >> and caching the data locally using fscache. After booting the clients, > >> most data is served from fscache and only a few requests hit the NFS > >> server. But after some minutes of operation (which typically includes a > >> lot of cyclic data reading for us), fewer and fewer files are served > >> from fscache and most are served by the NFS server. > >> It seems that this has something to do with the files being also in the > >> pagecache. If I periodcally drop the pagecache with "echo 3 > > >> /proc/sys/vm/drop_caches", then most of the files are served from > >> fscache again. > >> > >> Is this a known problem? If not, do you have any suggestion how I can > >> try to find the root cause? > >> > > > > Yes this is most likely a known problem with a fix now in the > > mm-unstable branch at > > git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm > > If it's the same problem, take these 3 patches and that should fix it: > > 6fbefbe174ca mm: call folio_mapping() inside folio_needs_release() > > 04cb8ddab902 mm, netfs, fscache: stop read optimisation when folio > > removed from pagecache > > 854fc8a567ab mm: merge folio_has_private()/filemap_release_folio() call pairs > > > > The main patch that fixes it is "04cb8ddab902 mm, netfs, fscache: Stop > > read optimisation when folio removed from pagecache" but there's a > > prerequisite patch and a fixup patch. > > I ran some tests yesterday and today, and it seems that these patches > fix the problem completely. Thanks! > Great! Thank you for the report, and follow up verification!. > > > > > >> Thank you in advance! > >> > >> Best regards, > >> > >> Ole > >> > >> -- > >> Linux-cachefs mailing list > >> Linux-cachefs@xxxxxxxxxx > >> https://listman.redhat.com/mailman/listinfo/linux-cachefs > >> > > > -- Linux-cachefs mailing list Linux-cachefs@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/linux-cachefs
