Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262459AbTEAF3b (ORCPT ); Thu, 1 May 2003 01:29:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262473AbTEAF3b (ORCPT ); Thu, 1 May 2003 01:29:31 -0400 Received: from e31.co.us.ibm.com ([32.97.110.129]:57279 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id S262459AbTEAF3a (ORCPT ); Thu, 1 May 2003 01:29:30 -0400 Message-ID: <3EB0B346.1080805@us.ibm.com> Date: Wed, 30 Apr 2003 22:40:22 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.0) Gecko/20020623 Debian/1.0.0-0.woody.1 X-Accept-Language: en MIME-Version: 1.0 To: Gerrit Huizenga CC: Robert Love , viro@parcelfarce.linux.theplanet.co.uk, Andrew Morton , Rick Lindsley , solt@dns.toxicfilms.tv, linux-kernel@vger.kernel.org, frankeh@us.ibm.com Subject: Re: must-fix list for 2.6.0 References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1846 Lines: 43 Gerrit Huizenga wrote: > Which affects JVM in most cases. NPTL based JVMs will possibly > obviate that problem. My guess is that in the JVM case, they have > a bad locking model (er, a simpler 2-tier locking model instead of > a more correct and complex 3-tier locking model) for their threading > operations. As a result, they use either sched_yield() or used > to use pause() to relinquish the processor so the world could change > and they could acquire the locks they wanted. The JVM's extensive use of sched_yield(), plus the HT scheduler causes some pretty undesirable behaviour in SPECjbb(tm) (see disclaimer). It starves some pieces of the benchmark so badly, that the benchmark results are invalid. We also start to get tons of idle time as the load goes up. In case anybody is curious, we're trying to share more of the data that we collect when we run the benchmarks. Most of it us useless, but someone might find a gem or two. Here are two runs, one with HT, and the other without. There's also a pretty busy gnuplot graph in there: http://www.sr71.net/prof/jbb/elm3a2/ The benchmark results can be found in: /benchmark/SPECjbb.* Disclaimer: SPEC (tm) and the benchmark name SPECjbb (tm) are registered trademarks of the Standard Performance Evaluation Corporation. The benchmarking was conducted for research purposes only and were non-compliant with the following deviations from the rules: 1. It was run on hardware that does not meet the SPEC availability-to-the public criteria. The machine was an engineering sample. -- Dave Hansen haveblue@us.ibm.com - 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/