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Date: Mon, 03 Dec 2007 17:35:07 +0800 From: "Zhang, Yanmin" <yanmin_zhang@...ux.intel.com> To: Nick Piggin <nickpiggin@...oo.com.au> Cc: Ingo Molnar <mingo@...e.hu>, Arjan van de Ven <arjan@...radead.org>, Andrew Morton <akpm@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: sched_yield: delete sysctl_sched_compat_yield On Mon, 2007-12-03 at 20:17 +1100, Nick Piggin wrote: > On Monday 03 December 2007 19:45, Ingo Molnar wrote: > > * Nick Piggin <nickpiggin@...oo.com.au> wrote: > > > On Friday 30 November 2007 21:08, Ingo Molnar wrote: > > > > * Nick Piggin <nickpiggin@...oo.com.au> 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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