On Thu, Oct 25, 2018 at 7:17 AM Matt Benjamin <mbenjami@xxxxxxxxxx> wrote: > > To clarify, what is the result with "-g -O2"? > there is no slowdown in RelWithDebInfo mode > Matt > > On Wed, Oct 24, 2018 at 5:59 PM, Ricardo Dias <rdias@xxxxxxxx> wrote: > > > > > > On 24/10/2018 21:54, Gregory Farnum wrote: > >> Do we understand why debug mode got so much slower? Is there something > >> we can do to improve it? > > > > I believe the reason for the slowdown is due to the increase of number > > of functions that are used in the new implementation. While in the > > previous implementation, the state machine was implemented with just two > > big functions (with a switch/case block in each), the new implementation > > uses one function per protocol state. > > I'm not familiar with what the compiler generates in Debug mode, but I > > imagine that now there are much more debug symbols to track, and less > > optimizations that the compiler can preform without confusing the > > debugger tools. > > > > I currently don't see a way to improve the performance in Debug mode. > > One thing we can do though is to also check the performance when > > compiling in RelWithDebugInfo mode. If it preforms similar to the > > Release mode, at least we still have debug symbols to help in > > identifying some problems. > > > >> > >> We are for instance seeing new issues with the messenger in our > >> testing, apparently because the reduced speed opens up race conditions > >> much wider. In this case that's good for us, but it could easily go > >> the other way as well and I'm concerned about not finding new issues > >> in our testing if the difference is so substantial compared to what > >> will be deployed by users. > > > > Maybe we can build packages for the binaries compiled with the two modes > > (Debug and Release) and be able to specify which one to use in each test > > run. > > > >> -Greg > >> On Wed, Oct 24, 2018 at 3:18 AM Yan, Zheng <ukernel@xxxxxxxxx> wrote: > >>> > >>> Only ceph complied in debug mode has the regression. Ceph complied in > >>> release mode has no regression. Sorry for the noisy. > >>> > >>> Yan, Zheng > >>> > >>> > >>> > >>> On Wed, Oct 24, 2018 at 1:46 PM Yan, Zheng <ukernel@xxxxxxxxx> wrote: > >>>> > >>>> Hi, > >>>> > >>>> Yesterday I checked how fast ceph-mds can process requests (a client > >>>> keeps sending getattr request of root inode). Requests rate I got is > >>>> only about half of same test I did a few weeks ago. Perf profile of > >>>> ceph-mds shows that messenger functions used more CPU time compared to > >>>> mimic code. Performance result and perf profiles are at > >>>> http://tracker.ceph.com/issues/36561. > >>>> > >>>> Regards > >>>> Yan, Zheng > >> > > > > -- > > Ricardo Dias > > Senior Software Engineer - Storage Team > > SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, > > HRB 21284 > > (AG Nürnberg) > > > > > > -- > > Matt Benjamin > Red Hat, Inc. > 315 West Huron Street, Suite 140A > Ann Arbor, Michigan 48103 > > http://www.redhat.com/en/technologies/storage > > tel. 734-821-5101 > fax. 734-769-8938 > cel. 734-216-5309
