From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: [RESEND] [PATCH] readahead:add blk_run_backing_dev Date: Mon, 03 Aug 2009 13:20:21 +0400 Message-ID: <4A76ABD5.9020808@vlnb.net> References: <4A3CD62B.1020407@vlnb.net> <4A60C1A8.9020504@vlnb.net> <4A641AAC.9030300@vlnb.net> <4A6DA77B.7080600@vlnb.net> <4A6F4C81.10600@vlnb.net> <4A7338AF.8010407@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: fengguang.wu@intel.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com, Alan.Brunelle@hp.com, linux-fsdevel@vger.kernel.org, jens.axboe@oracle.com, randy.dunlap@oracle.com, Bart Van Assche To: Ronald Moesbergen Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Ronald Moesbergen, on 08/03/2009 01:15 PM wrote: > 2009/7/31 Vladislav Bolkhovitin : >> OK, as I expected, on the SCST level everything is clear and the forced >> ordering change didn't change anything. >> >> But still, a single read stream must be the fastest from single thread. >> Otherwise, there's something wrong somewhere in the I/O path: block layer, >> RA, I/O scheduler. And, apparently, this is what we have and should find out >> the cause. >> >> Can you check if noop on the target and/or initiator makes any difference? >> Case 5 with 1 and 2 threads will be sufficient. > > That doesn't seem to help: > > client kernel: 2.6.26-15lenny3 (debian) > server kernel: 2.6.29.5 with readahead-context, blk_run_backing_dev > and io_context, forced_order > > With one IO thread: > 5) client: default, server: default (server noop, client noop) > blocksize R R R R(avg, R(std R > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS) > 67108864 17.612 21.113 21.355 51.532 4.680 0.805 > 33554432 18.329 18.523 19.049 54.969 0.891 1.718 > 16777216 18.497 18.219 17.042 57.217 2.059 3.576 > > With two threads: > 5) client: default, server: default (server noop, client noop) > blocksize R R R R(avg, R(std R > (bytes) (s) (s) (s) MB/s) ,MB/s) (IOPS) > 67108864 17.436 18.376 20.493 54.807 3.634 0.856 > 33554432 17.466 16.980 18.261 58.337 1.740 1.823 > 16777216 18.222 17.567 18.077 57.045 0.901 3.565 And with client cfq, server noop? > Ronald. >