From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262719AbTLIDhP (ORCPT ); Mon, 8 Dec 2003 22:37:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262725AbTLIDhP (ORCPT ); Mon, 8 Dec 2003 22:37:15 -0500 Received: from fw.osdl.org ([65.172.181.6]:39844 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S262719AbTLIDhG (ORCPT ); Mon, 8 Dec 2003 22:37:06 -0500 Date: Mon, 8 Dec 2003 19:37:00 -0800 From: Mark Wong To: Nick Piggin Cc: linux-kernel@vger.kernel.org, osdldbt-general@lists.sourceforge.net Subject: Re: hyperthreading performance with dbt-2 on 2.6.0-test11 Message-ID: <20031208193700.B6933@osdlab.pdx.osdl.net> Mail-Followup-To: Nick Piggin , linux-kernel@vger.kernel.org, osdldbt-general@lists.sourceforge.net References: <200312082354.hB8NsqZ17359@mail.osdl.org> <3FD51496.5000500@cyberone.com.au> <20031208191258.A6933@osdlab.pdx.osdl.net> <3FD5413D.1000400@cyberone.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <3FD5413D.1000400@cyberone.com.au>; from piggin@cyberone.com.au on Tue, Dec 09, 2003 at 02:27:57PM +1100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Oops, sorry, I must of overlooked it because it looked like garbage. Um, I'll copy it anyway just in case it helps, but it didn't echo cleanly for some reason: <4>>UU:b e 4 aF AGSr u7f e0d0ress P00s03t80xe eainredc pcinci8 g eip::00000002 0 espo ince: cd11e1fbr cdx<40 a00v60t : f5c41d04 0d0: 000 es: 0000 ss: 0068 On Tue, Dec 09, 2003 at 02:27:57PM +1100, Nick Piggin wrote: > > > Mark Wong wrote: > > >On Tue, Dec 09, 2003 at 11:17:26AM +1100, Nick Piggin wrote: > > > >> > >>markw@osdl.org wrote: > >> > >> > >>>Hello, I have some data with hyperthreading I wanted to share. > >>> > >>>I've seen about a 15% performance decrease in performance on a 4-way > >>>Xeon system when I enable hyperthreading for my DBT-2 workload. I also > >>>gave Ingo's test11-C1 patch that someone pointed me to a try and only > >>>saw a 12% decrease. Has anyone found this to be common with any specific > >>>workloads? > >>> > >>>I'm not really sure what to look for, but I do see some changes in the > >>>readprofile data, which I've copied in part below. It appears that the > >>>count of schedule, __make_request, and try_to_wake_up are the only > >>>functions at the top of the profile that are significantly different. > >>>The links I have posted also have pointers to oprofile data as well as > >>>annotated assembly source output, if that interests anyone. If I can > >>>provide any other details, let me know. > >>> > >>> > >>Hi Mark, > >>It could be cache contention which I think is typically the reason > >>hyperthreading can hurt performance. Its basically impossible for > >>the scheduler to correct this automatically (access to performance > >>counters might make it slightly less impossible). > >> > >>Probably the CPU hotplug interface would enable a tool to effectively > >>turn HT on or off and it would be up to an administrator to tune > >>performance. > >> > >>You could try my scheduler patchset if you like. I have recently got > >>HT support working (its against test11, you need to turn CONFIG_SMT > >>on), although if Ingo's patch doesn't help much, mine probably won't > >>either. > >> > > > >Hi Nick, > > > >Went ahead and tried your patch, but it looks like something's wrong. If > >this helps any: > > > > Doh. OK, did you manage to capture anything above this? > > > > >Process postmaster (pid: 1086, threadinfo=f5c40000 task=f5c586b0) > >Stack: f5c5007b 0000007b ffffffff c011f488 00000060 00010046 00000005 c322ccc0 > > c322c060 00000002 f5c5bdbc f686cb90 f686cb90 f5c41d4c f7f93940 f5ca6080 > > 00000007 00000000 c322ccc0 00006f12 03d99f34 0000033d f5c586b0 f5c41dbc > >Call Trace: [] schedule+0x380/0x705 > > [] sys_semtimedop+0x460/0x530 > > [] find_busiest_group+0x2bc/0x2e3 > > [] p4_check_ctrs+0xab/0x11b > > [] find_busiest_group+0x2bc/0x2e3 > > [] nmi_callback+0x25/0x29 > > [] buffered_rmqueue+0xea/0x199 > > [] nmi_stack_correct+0x1e/0x2e > > [] __alloc_pages+0xaf/0x334 > > [] generic_file_aio_write_nolock+0x298/0xa9e > > [] do_anonymous_page+0x16a/0x28b > > [] handle_mm_fault+0x101/0x1ad > > [] do_page_fault+0x2fa/0x4fc > > [] rebalance_tick+0x8a/0x91 > > [] oprofile_add_sample+0x9b/0x117 > > [] p4_check_ctrs+0xab/0x11b > > [] sys_ipc+0x61/0x2ae > > [] nmi_callback+0x25/0x29 > > [] do_nmi+0x39/0x5a > > [] sysenter_past_esp+0x52/0x71 > > > >Code: Bad EIP value. > > > > > > > > > > -- Mark Wong - - markw@osdl.org Open Source Development Lab Inc - A non-profit corporation 12725 SW Millikan Way - Suite 400 - Beaverton, OR 97005 (503) 626-2455 x 32 (office) (503) 626-2436 (fax) http://developer.osdl.org/markw/