Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754355AbXLFQ3l (ORCPT ); Thu, 6 Dec 2007 11:29:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752713AbXLFQ3d (ORCPT ); Thu, 6 Dec 2007 11:29:33 -0500 Received: from ccs17.jlab.org ([129.57.35.82]:38795 "EHLO ccs17.jlab.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752396AbXLFQ3c (ORCPT ); Thu, 6 Dec 2007 11:29:32 -0500 Message-ID: <47582367.6060602@jlab.org> Date: Thu, 06 Dec 2007 11:29:27 -0500 From: Jie Chen Organization: Jefferson Lab User-Agent: Thunderbird 2.0.0.9 (X11/20071031) MIME-Version: 1.0 To: Ingo Molnar CC: Simon Holm Th??gersen , Eric Dumazet , linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4 References: <20071205154014.GA6491@elte.hu> <4756D058.1070500@jlab.org> <20071205164723.GA25641@elte.hu> <4756E44E.8080607@jlab.org> <20071205200343.GA14570@elte.hu> <475708A7.4030708@jlab.org> <20071205204645.GC25694@elte.hu> <47570F83.6040601@jlab.org> <20071205210222.GA30089@elte.hu> <47572353.4040606@jlab.org> <20071206104318.GB30838@elte.hu> In-Reply-To: <20071206104318.GB30838@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2750 Lines: 88 Ingo Molnar wrote: > * Jie Chen wrote: > >>> not "BARRIER time". I've re-read the discussion and found no hint >>> about how to build and run a barrier test. Either i missed it or it's >>> so obvious to you that you didnt mention it :-) >>> >>> Ingo >> Hi, Ingo: >> >> Did you do configure --enable-public-release? My qmt is for qcd >> calculation (one type of physics code) [...] > > yes, i did exactly as instructed. > >> [...]. Without the above flag one can only test PARALLEL overhead. >> Actually the PARALLEL benchmark has the same behavior as the BARRIER. >> Thanks. > > hm, but PARALLEL does not seem to do that much context switching. So > basically you create the threads and do a few short runs to establish > overhead? Threads do not get fork-balanced at the moment - but turning > it on would be easy. Could you try the patch below - how does it impact > your results? (and please keep affinity setting off) > > Ingo > > -----------> > Subject: sched: reactivate fork balancing > From: Ingo Molnar > > reactivate fork balancing. > > Signed-off-by: Ingo Molnar > --- > include/linux/topology.h | 3 +++ > 1 file changed, 3 insertions(+) > > Index: linux/include/linux/topology.h > =================================================================== > --- linux.orig/include/linux/topology.h > +++ linux/include/linux/topology.h > @@ -103,6 +103,7 @@ > .forkexec_idx = 0, \ > .flags = SD_LOAD_BALANCE \ > | SD_BALANCE_NEWIDLE \ > + | SD_BALANCE_FORK \ > | SD_BALANCE_EXEC \ > | SD_WAKE_AFFINE \ > | SD_WAKE_IDLE \ > @@ -134,6 +135,7 @@ > .forkexec_idx = 1, \ > .flags = SD_LOAD_BALANCE \ > | SD_BALANCE_NEWIDLE \ > + | SD_BALANCE_FORK \ > | SD_BALANCE_EXEC \ > | SD_WAKE_AFFINE \ > | SD_WAKE_IDLE \ > @@ -165,6 +167,7 @@ > .forkexec_idx = 1, \ > .flags = SD_LOAD_BALANCE \ > | SD_BALANCE_NEWIDLE \ > + | SD_BALANCE_FORK \ > | SD_BALANCE_EXEC \ > | SD_WAKE_AFFINE \ > | BALANCE_FOR_PKG_POWER,\ Hi, Ingo: I did patch the header file and recompiled the kernel. I observed no difference (two threads overhead stays too high). Thank you. -- ############################################### Jie Chen Scientific Computing Group Thomas Jefferson National Accelerator Facility 12000, Jefferson Ave. Newport News, VA 23606 (757)269-5046 (office) (757)269-6248 (fax) chen@jlab.org ############################################### -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/