Hi Sage > -----Original Message----- > From: Sage Weil [mailto:sage@xxxxxxxxxxxx] > Sent: 25 November 2015 17:38 > To: Nick Fisk <nick@xxxxxxxxxx> > Cc: 'ceph-users' <ceph-users@xxxxxxxxxxxxxx>; ceph-devel@xxxxxxxxxxxxxxx; > 'Mark Nelson' <mnelson@xxxxxxxxxx> > 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. Would it be useful for me to run all 3 versions (Old, this and mine) through the same performance test I did before? Also I saw pull request 6623, is it still relevant to get the list order right? Thanks for your support on this. Nick > > Thanks! > sage _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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