Hi, Yan, Zheng wrote :
>> http://tracker.ceph.com/issues/11059 >> > > It's a bug in ACL code, I have updated http://tracker.ceph.com/issues/11059 Ok, thanks. I have seen and I will answer quickly. ;) >> I'm still surprised by such times. For instance, It seems to me >> that, with a mounted nfs share, commands like "ls -la" are very >> fast in comparison (with a directory which contains the same number >> of files). Can anyone explain to me why there is a such difference >> between the nfs case and the cephfs case? This is absolutely not a >> criticism but it's just to understand the concepts that come into >> play. In the case of "ls -al" ie just reading (it is assumed that >> there is no writing on the directory), the nfs and the cephfs cases >> seem to me very similar: the client just requests a stat on each file >> in the directory. Am I wrong? > > NFS has no cache coherence mechanism. It can't guarantee one client always > see other client's change. Ah ok, I didn't know that. Indeed, now I understand that can generate performance impact. > The time variation is caused cache coherence. when client has valid > information > in its cache, 'stat' operation will be fast. Otherwise the client need to send > request to MDS and wait for reply, which will be slow. Ok, thanks a lot for your explanations. Regards. -- François Lafont _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
