From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe Subject: Re: speed decrease since firefly,giant,hammer the 2nd try Date: Tue, 10 Feb 2015 20:13:23 +0100 Message-ID: <54DA5853.3070504@profihost.ag> References: <54DA541E.9000608@profihost.ag> <54DA578F.3000900@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ph.de-nserver.de ([85.158.179.214]:43805 "EHLO mail-ph.de-nserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752511AbbBJTNW (ORCPT ); Tue, 10 Feb 2015 14:13:22 -0500 In-Reply-To: <54DA578F.3000900@redhat.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Mark Nelson , "ceph-devel@vger.kernel.org" Am 10.02.2015 um 20:10 schrieb Mark Nelson: > > > On 02/10/2015 12:55 PM, Stefan Priebe wrote: >> Hello, >> >> last year in june i already reported this but there was no real result. >> (http://lists.ceph.com/pipermail/ceph-users-ceph.com/2014-July/041070.html) >> >> >> I then had the hope that this will be fixed itself when hammer is >> released. Now i tried hammer an the results are bad as before. >> >> Since firefly librbd1 / librados2 are 20% slower for 4k random iop/s >> than dumpling - this is also the reason why i still stick to dumpling. >> >> I've now modified my test again to be a bit more clear. >> >> Ceph cluster itself completely dumpling. >> >> librbd1 / librados from dumpling (fio inside qemu): 23k iop/s for random >> 4k writes >> >> - stopped qemu >> - cp -ra firefly_0.80.8/usr/lib/librados.so.2.0.0 /usr/lib/ >> - cp -ra firefly_0.80.8/usr/lib/librbd.so.1.0.0 /usr/lib/ >> - start qemu >> >> same fio, same qemu, same vm, same host, same ceph dumpling storage, >> different librados / librbd: 16k iop/s for random 4k writes >> >> What's wrong with librbd / librados2 since firefly? > > Hi Stephen, > > Just off the top of my head, some questions to investigate: > > What happens to single op latencies? How to test this? > Does enabling/disabling RBD cache have any effect? I've it enabled on both through qemu write back setting. > How's CPU usage? (Does perf report show anything useful?) > Can you get trace data? I'm not familiar with trace or perf - what should do exactly? Stefan > Mark > >> >> Greets, >> Stefan >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html