On Wed, Jun 24, 2015 at 10:29 PM, Stefan Priebe <s.priebe@xxxxxxxxxxxx> wrote: > > Am 24.06.2015 um 19:53 schrieb Ilya Dryomov: >> >> On Wed, Jun 24, 2015 at 8:38 PM, Stefan Priebe <s.priebe@xxxxxxxxxxxx> >> wrote: >>> >>> >>> Am 24.06.2015 um 16:55 schrieb Nick Fisk: >>>> >>>> >>>> That kernel probably has the bug where tcp_nodelay is not enabled. That >>>> is fixed in Kernel 4.0+, however also in 4.0 blk-mq was introduced which >>>> brings two other limitations:- >>> >>> >>> >>> blk-mq is terrible slow. That's correct. >> >> >> Is that a general sentiment or your experience with rbd? If the >> latter, can you describe your workload and provide some before and >> after blk-mq numbers? We'd be very interested in identifying and >> fixing any performance regressions you might have on blk-mq rbd. > > > oh i'm sorry. I accidently compiled blk-mq into the kernel when 3.18.1 came > out and i was wondering why my I/O waits on my ceph osds where doubled or > even tripled. After reverting back to cfq everything was fine again. I > didn't digged deeper into it as i thought blk-mq is experimental in 3.18. That doesn't make sense - rbd was switched to blk-mq in 4.0. Or did you try to apply the patch from the mailing list to 3.18? > > If you're willing to assist i can give it a try - but need the patches you > mention first (git commit ids?). No commit ids as the patches are not upstream yet. I have everything gathered in testing+blk-mq-plug branch of ceph-client.git: https://github.com/ceph/ceph-client/tree/testing%2Bblk-mq-plug A deb (ubuntu, debian, etc): http://gitbuilder.ceph.com/kernel-deb-precise-x86_64-basic/ref/testing_blk-mq-plug/linux-image.deb An rpm (fedora, centos, rhel): http://gitbuilder.ceph.com/kernel-rpm-centos7-x86_64-basic/ref/testing_blk-mq-plug/kernel.x86_64.rpm These are built with slightly stripped down distro configs so it should boot most boxes. Thanks, Ilya _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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