> -----Original Message----- > From: ceph-devel-ow...@vger.kernel.org [mailto:ceph-devel- > ow...@vger.kernel.org] On Behalf Of Sage Weil > Sent: 25 November 2015 19:41 > To: Nick Fisk <n...@fisk.me.uk> > Cc: 'ceph-users' <ceph-users@lists.ceph.com>; ceph-de...@vger.kernel.org; > 'Mark Nelson' <mnel...@redhat.com> > Subject: RE: Cache Tiering Investigation and Potential Patch > > On Wed, 25 Nov 2015, Nick Fisk wrote: > > Hi Sage > > > > > -----Original Message----- > > > From: Sage Weil [mailto:s...@newdream.net] > > > Sent: 25 November 2015 17:38 > > > To: Nick Fisk <n...@fisk.me.uk> > > > Cc: 'ceph-users' <ceph-users@lists.ceph.com>; > > > ceph-de...@vger.kernel.org; 'Mark Nelson' <mnel...@redhat.com> > > > Subject: Re: Cache Tiering Investigation and Potential Patch > > > > > > On Wed, 25 Nov 2015, Nick Fisk wrote: > > > > Presentation from the performance meeting. > > > > > > > > I seem to be unable to post to Ceph-devel, so can someone please > > > > repost there if useful. > > > > > > Copying ceph-devel. The problem is just that your email is HTML- > formatted. > > > If you send it in plaintext vger won't reject it. > > > > Right ok, let's see if this gets through. > > > > > > > > > I will try and get a PR sorted, I realise that this change > > > > modifies the way the cache was originally designed but I think it > > > > provides a quick win for the performance increase involved. If > > > > there are plans for a better solution in time for the next > > > > release, then I would be really interested in working to that goal > instead. > > > > > > It's how it was intended/documented to work, so I think this falls > > > in the 'bug fix' category. I did a quick PR here: > > > > > > https://github.com/ceph/ceph/pull/6702 > > > > > > Does that look right? > > > > Yes I think that should definitely be an improvement. I can't quite > > get my head around how it will perform in instances where you miss 1 > > hitset but all others are a hit. Like this: > > > > H H H M H H H H H H H H > > > > And recency is set to 8 for example. It maybe that it doesn't have > > much effect on the overall performance. It might be that there is a > > strong separation of really hot blocks and hot blocks, but this could > > turn out to be a good thing. > > Yeah... In the above case recency 3 would be enough (or 9, depending on > whether that's chronological or reverse chronological order). Doing an N out > of M or similar is a bit more flexible and probably something we should add > on top. (Or, we could change recency to be N/M instead of just > N.)
N out of M, is that similar to what I came up with but combined with the N most recent sets? If you can wait a couple of days I will run the PR in its current state through my test box and see how it looks. Just a quick question, is there a way to just make+build the changed files/package or select just to build the main ceph.deb. I'm just using " sudo dpkg-buildpackage" at the moment and its really slowing down any testing I'm doing waiting for everything to rebuild. > > > Would it be useful for me to run all 3 versions (Old, this and mine) > > through the same performance test I did before? > > If you have time, sure! At the very least it'd be great to see the new > version > go through the same test. > > > Also I saw pull request 6623, is it still relevant to get the list > > order right? > > Oh right, I forgot about that one. I'll incorporate that fix and then you can > test that version. > > Thanks! > sage > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the > body of a message to majord...@vger.kernel.org More majordomo info at > http://vger.kernel.org/majordomo-info.html _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
