On Tue, 2 Jul 2019, Dan van der Ster wrote:
Hi,
Are there any plans to implement a per-client throttle on mds client requests?
We just had an interesting case where a new cephfs user was hammering an mds from several hosts. In the end we found that their code was doing:
while d=getafewbytesofdata(): f=open(file.dat) f.append(d) f.close()
By changing their code to:
f=open(file.dat) while d=getafewbytesofdata(): f.append(d) f.close()
it completely removes their load on the mds (for obvious reasons).
This is a tangential point, but: at some point in the past at least the above two code blcoks used to incur the same load on the MDS because the client would only asynchronously release the caps back to the MDS. Did we change that behavior? Maybe we can restore it, but with a very a short delay, so that we cover patterns like the above? sage
In a multi-user environment it's hard to scrutinize every user's application, so we'd prefer to just throttle down the client req rates (and let them suffer from the poor performance).
Thoughts?
Thanks,
Dan _______________________________________________ Dev mailing list -- dev@ceph.io To unsubscribe send an email to dev-leave@ceph.io