From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from merlin.infradead.org ([205.233.59.134]:41005 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755474Ab3EVMZn (ORCPT ); Wed, 22 May 2013 08:25:43 -0400 Date: Wed, 22 May 2013 14:25:25 +0200 From: Jens Axboe Subject: Re: output - aggregate read bandwitdh Message-ID: <20130522122525.GK9714@kernel.dk> References: <20130518122211.GM19781@kernel.dk> <20130522085736.GE9714@kernel.dk> <20130522101554.GG9714@kernel.dk> <20130522101858.GH9714@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Edoardo Comar Cc: fio@vger.kernel.org On Wed, May 22 2013, Edoardo Comar wrote: > > > So 67bf982340d95ca98098ea050b54b4c7adb116c0 is the first bad commit, > > > funky. Ah I think I see what it is, hang on. > > > > http://git.kernel.dk/? > > p=fio.git;a=commit;h=4b20c6814d4742e27a68f8a740a955283869fbcd > > > > If you git pull, you'll get that. Please see if that makes it behave > > like 2.0.13 for you. > > > > Thanks, > this has fixed the read aggrb reported value to be unreasonably high > however the value is now significantly lower than 2.0.13 it's about 1/2 > while the write value is very comparable. > Please find the outputs below. This is due to the change in thinktime, fixing the unreasonable latencies. Effectively it reduces your queue depth to what thinktime_blocks is set to, which is 1 by default. Even if set to the queue depth, you will still be completely draining the software queue for every N thinktime_blocks. I'm guessing your device has write caching enabled, hence the change is basically only apparent on reads. The writes queue up nicely on the hw side still. -- Jens Axboe