On Thu, Apr 4, 2019 at 10:18 AM Sam Just <sjust@xxxxxxxxxx> wrote: > > I don't think we're cheating, as such. I think the messenger and the > ObjectStore implementation will indeed dominate the overall cpu usage > and latency for reads in the common case for both classic and crimson, > so the setup we've got for crimson is probably reasonable. If we're > actually worried about it, we could probably short-circuit the classic > osd in the same way and get numbers that way? i think Radoslaw already did so in https://github.com/ceph/ceph/pull/24962. and per our latest test result [1], crimson-osd still outperforms the shortcut version. [1] https://gist.github.com/tchaikov/6a24b13f5397e0b9985460e64a7c00a4 > > Actually adding the checks (by which I mean whatever is required for > crimson to behave like an osd, not necessarily what's in classic) is yes, that's also my understanding. > pretty much implementing the full read and write paths for crimson, so > I'd guess that's where we're going anyway? yeah. guess i just wanted to be more conservative on where we are. =) > -Sam > > > On Wed, Apr 3, 2019 at 5:35 AM kefu chai <tchaikov@xxxxxxxxx> wrote: > > > > in today's standup meeting, we were discussing the apple-to-apple > > comparison. i think it still matters to have a rough apple-to-apple > > comparison to make sure we don't cut corners and hence won't be > > over-optimistic when benchmarking crimson-osd. > > > > if we are "cheating" and just connecting the messenger and backend > > store, skipping the critical factors that have significant impacts on > > the performance in classic OSD in normal i/o patterns. our test result > > won't be representative. > > > > i think one of the reasons why we implemented the read path first is > > that it is a typical i/o operation that we can have with minimal > > efforts. if the various checks are playing a significant role slowing > > down OSD, then we should at least understand if they still apply in > > crimson-osd. if yes, we should implement them, i guess. checksum > > verification based on object-info might be one of them. probably we > > can indeed skip this step, assuming bluestore will be dominant very > > soon. > > > > > > -- > > Regards > > Kefu Chai -- Regards Kefu Chai
