From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 1 Apr 2016 16:04:12 +1100 From: Dave Chinner To: Jens Axboe Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [PATCHSET v3][RFC] Make background writeback not suck Message-ID: <20160401050411.GW11812@dastard> References: <1459350477-16404-1-git-send-email-axboe@fb.com> <20160331082433.GO11812@dastard> <56FD344F.70908@fb.com> <56FD4E70.3090203@fb.com> <20160401005608.GU11812@dastard> <56FDEB1A.2030404@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56FDEB1A.2030404@fb.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: On Thu, Mar 31, 2016 at 09:29:30PM -0600, Jens Axboe wrote: > On 03/31/2016 06:56 PM, Dave Chinner wrote: > >I'm not changing the host kernels - it's a production machine and so > >it runs long uptime testing of stable kernels. (e.g. catch slow > >memory leaks, etc). So if you've disabled throttling in the guest, I > >can't test the throttling changes. > > Right, that'd definitely hide the problem for you. I'll see if I can > get it in a reproducible state and take it from there. > > On your host, you said it's SCSI backed, but what does the device look like? HW RAID 0 w/ 1GB FBWC (dell h710, IIRC) of 2x200GB SATA SSDs (actually 256GB, but 25% of each is left as spare, unused space). Sustains about 35,000 random 4k write IOPS, up to 70k read IOPS. Cheers, Dave. -- Dave Chinner david@fromorbit.com