I just did an interesting experiment. If I run the command 'lfs df' in a tight loop, the reint_statfs counters increments once but if I stick in a sleep 1, it increments it for every call. is this a bug or a feature? Is it doing some kind of short-lived cache lookup in the first can but not the second? -mark
Kilian CAVALOTTI wrote: > Hi Mark, > > >> useful. I suppose one might also make that argument about things like >> statfs, getattr - the only time I was able to make them change was in >> response to lfs commands. Might that logic also be applied to >> extended attributes and acl counters which I suspect also fall into >> the category of slowly changing counters? >> > > If you have ACLs enabled on your MDS, then every "ls -l" will induce > getxattr()s and the mds_getxattr counter will be increased by as much. > So this can change quickly. mds_setxattr, on the other hand, may change > less often, since you usually set ACLs less often than you list files. > But it can still be interesting to see if mds_setxattr goes through the > roof. > > >> On the other hand, it seems like the 'reint' counters are the ones >> that tend to change a lot. Perhaps a clue is they're all prefaced >> with reint which leads me to ask if there is some simple definition >> of what reint actually means other than 'reintegrated operations'? >> > > I'd bet on "request identification" or something along those lines. > > >> Perhaps such a definition will help explain why setattr is a reint >> counter but getattr is not. In fact, I have seen getattr_lock change >> a lot more than getattr. What is the difference between the 2 >> (obviously the latter is some sort of lock but it must be used more >> than just when incrementing getattr since they don't change >> together)? >> > > I'm only speculating here, but I believe that extended attributes which > are modifiable by a user on a client (like ACLs) are counted in > *_xattr, while internal extended attributes used by the MDS, are > counted in gettatr. > > >> That all said, it feels like the data to report is all the reints, >> getattr, getattr_lock and sync. >> > > I would also be interested in seeing (dis)connect (this can probably > reveal network problems, if it increases too much), as well as quotactl > and get/setxattr, since I use quotas and ACLs. :) > > > Cheers, > _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
