On Thu, 2020-11-12 at 23:17 +0800, Sage Meng wrote: > Hi All, > > Cephfs kernel client is influenced by kernel page cache when we > write data to it, outgoing data will be huge when os starts to flush > page cache. So Is there a way to make Cephfs kernel client to send > data to ceph cluster smoothly when buffer io is used ? Better a way > that only influence Ceph IO not the whole system IO. Not really. The ceph client just does what the VM subsys asks it to do. If the VM says "write out these pages", then it'll do it -- otherwise they'll just sit there dirty. Usually you need to tune things like the dirty_ratio and dirty_background_ratio to smooth this sort of thing out, but those are system-wide knobs. Another alternative is to strategically fsync or syncfs from time to time, but that's sort of outside the scope of the kernel client. -- Jeff Layton <jlayton@xxxxxxxxxx>
