From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752574AbXLCJhu (ORCPT ); Mon, 3 Dec 2007 04:37:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751402AbXLCJhn (ORCPT ); Mon, 3 Dec 2007 04:37:43 -0500 Received: from mga10.intel.com ([192.55.52.92]:13272 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750908AbXLCJhm (ORCPT ); Mon, 3 Dec 2007 04:37:42 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.23,243,1194249600"; d="scan'208";a="221944644" Subject: Re: sched_yield: delete sysctl_sched_compat_yield From: "Zhang, Yanmin" To: Nick Piggin Cc: Ingo Molnar , Arjan van de Ven , Andrew Morton , LKML In-Reply-To: <200712032017.19661.nickpiggin@yahoo.com.au> References: <1196155985.25646.31.camel@ymzhang> <200712031527.57129.nickpiggin@yahoo.com.au> <20071203084557.GA13156@elte.hu> <200712032017.19661.nickpiggin@yahoo.com.au> Content-Type: text/plain; charset=utf-8 Date: Mon, 03 Dec 2007 17:35:07 +0800 Message-Id: <1196674507.25646.134.camel@ymzhang> Mime-Version: 1.0 X-Mailer: Evolution 2.9.2 (2.9.2-2.fc7) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2007-12-03 at 20:17 +1100, Nick Piggin wrote: > On Monday 03 December 2007 19:45, Ingo Molnar wrote: > > * Nick Piggin wrote: > > > On Friday 30 November 2007 21:08, Ingo Molnar wrote: > > > > * Nick Piggin wrote: > > > > > Haven't we been asking JVMs to use futexes or posix locking for years > > > > > and years now? [...] > > > > > > > > i'm curious, with what JVM was it tested and where's the source so i > > > > can fix their locking for them? Can the problem be reproduced with: > > > > > > Sure, but why shouldn't the compat behaviour be the default, and the > > > sysctl go away? > > > > > > It makes older JVMs work better, it is slightly closer to the old > > > behaviour, and it is arguably a less surprising result. > > > > as far as desktop apps such as firefox goes, the exact opposite is true. > > We had two choices basically: either a "more agressive" yield than > > before or a "less agressive" yield. Desktop apps were reported to hurt > > from a "more agressive" yield (firefox for example gets some pretty bad > > delays), so we defaulted to the less agressive method. (and we defaulted > > to that in v2.6.23 already) > > Yeah, I doubt the 2.6.23 scheduler will be usable for distros though... > > > > Really, in this sense volanomark is another > > test like dbench - we care about it but not unconditionally and in this > > case it's a really silly API use that is at the center of the problem. > > Sure, but do you whether _real_ java server applications are OK? I did a simple check of openjvm source codes and garbage collecter calls Thread.yield. It really has much impact on both Jrockit and openJVM although the regression percentage is different.