From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: idle array consuming cpu ??!! Date: Tue, 22 Jan 2008 17:53:29 -0500 Message-ID: <479673E9.8030301@tmr.com> References: <18323.53904.556620.19761@fisica.ufpr.br> <18323.61999.693738.678224@notabene.brown> <18325.21501.507878.267465@fisica.ufpr.br> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <18325.21501.507878.267465@fisica.ufpr.br> Sender: linux-raid-owner@vger.kernel.org To: Carlos Carvalho Cc: Neil Brown , linux-raid@vger.kernel.org List-Id: linux-raid.ids Carlos Carvalho wrote: > Neil Brown (neilb@suse.de) wrote on 21 January 2008 12:15: > >On Sunday January 20, carlos@fisica.ufpr.br wrote: > >> A raid6 array with a spare and bitmap is idle: not mounted and with no > >> IO to it or any of its disks (obviously), as shown by iostat. However > >> it's consuming cpu: since reboot it used about 11min in 24h, which is quite > >> a lot even for a busy array (the cpus are fast). The array was cleanly > >> shutdown so there's been no reconstruction/check or anything else. > >> > >> How can this be? Kernel is 2.6.22.16 with the two patches for the > >> deadlock ("[PATCH 004 of 4] md: Fix an occasional deadlock in raid5 - > >> FIX") and the previous one. > > > >Maybe the bitmap code is waking up regularly to do nothing. > > > >Would you be happy to experiment? Remove the bitmap with > > mdadm --grow /dev/mdX --bitmap=none > > > >and see how that affects cpu usage? > > Confirmed, removing the bitmap stopped cpu consumption. Looks like quite a bit of CPU going into idle arrays here, too. -- Bill Davidsen "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark