On Thu, Oct 22, 2015 at 2:55 PM, Burkhard Linke <Burkhard.Linke@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hi, > > > On 10/22/2015 02:54 AM, Gregory Farnum wrote: >> >> On Sun, Oct 18, 2015 at 8:27 PM, Yan, Zheng <ukernel@xxxxxxxxx> wrote: >>> >>> On Sat, Oct 17, 2015 at 1:42 AM, Burkhard Linke >>> <Burkhard.Linke@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: >>>> >>>> Hi, >>>> >>>> I've noticed that CephFS (both ceph-fuse and kernel client in version >>>> 4.2.3) >>>> remove files from page cache as soon as they are not in use by a process >>>> anymore. >>>> >>>> Is this intended behaviour? We use CephFS as a replacement for NFS in >>>> our >>>> HPC cluster. It should serve large files which are read by multiple jobs >>>> on >>>> multiple hosts, so keeping them in the page cache over the duration of >>>> several job invocations is crucial. >>> >>> Yes. MDS needs resource to track the cached data. We don't want MDS >>> use too much resource. >> >> So if I'm reading things right, the code to drop the page cache for >> ceph-fuse was added in https://github.com/ceph/ceph/pull/1594 >> (specifically 82015e409d09701a7048848f1d4379e51dd00892). I don't think >> it's actually needed for the cap trimming stuff or to prevent MDS >> cache pressure and it's actually not clear to me why it was added here >> anyway. But you do say the PR as a whole fixed a lot of bugs. Do you >> know if the page cache clearing was for any bugs in particular, Zheng? >> >> In general I think proactively clearing the page cache is something we >> really only want to do as part of our consistency and cap handling >> story, and file closes don't really play into that. I've pushed a >> TOTALLY UNTESTED (NOT EVEN COMPILED) branch client-pagecache-norevoke >> based on master to the gitbuilders. If it does succeed in building you >> should be able to download it and you can use it for testing, or >> cherry-pick the top commit out of git and build your own packages. >> Then set the (new to this branch) client_preserve_pagecache config >> option to true (default: false) and it should avoid flushing the page >> cache. > > > Thanks a lot for having a closer look at this. I'm currently preparing the > deployment of 0.94.4 (or 0.94.5 due to rbd bug), and need to add some > patches to ceph-fuse for correct permission handling. I'll cherry-pick the > changes of that branch and test the package. > > I have wrote patches for both kernel and fuse clients. they are under testing https://github.com/ceph/ceph/pull/6380 https://github.com/ceph/ceph-client/commit/dfbb503e4e12580fc3d2952269104f293b0ec7e8 > > Regards, > Burkhard > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |