Date: Tue, 31 May 2011 16:16:26 -0400 From: Jung-uk Kim <jkim@FreeBSD.org> To: Andriy Gapon <avg@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: [RFC] Enabling invariant TSC timecounter on SMP Message-ID: <201105311616.31256.jkim@FreeBSD.org> In-Reply-To: <4DE4CE82.4030301@FreeBSD.org> References: <201105241356.45543.jkim@FreeBSD.org> <4DE4CE82.4030301@FreeBSD.org>
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On Tuesday 31 May 2011 07:18 am, Andriy Gapon wrote: > on 24/05/2011 20:56 Jung-uk Kim said the following: > > I think it's about time to enable invariant TSC timecounter on > > SMP by default. Please see the attached patch. It is also > > available from here: > > > > http://people.freebsd.org/~jkim/tsc_smp_test4.diff > > > > avg convinced me enough that it should be an opt-out feature > > going forward. :-) > > Not sure if I really did that. > My position is this: > - if we think that TSC is SMP-safe then it should have the best > priority > - we should do our best to auto-guess if TSC is SMP-safe > unless a user explicitly overrides that property (either via > explicit testing or by making guesses based on CPU model or etc) I am sorry if I misunderstood your intention. However, I added explicit boot-time TSC sanity check (to do our best to auto-guess) and I think TSC is fairly SMP-safe. Hence, I thought that it is about time for the change. > > Comments? > > Perhaps I missed it, but I don't remember the "lowres" part of the > patch being discussed. No, it wasn't discussed with you. Do you see any problem with that code? Thanks, Jung-uk Kim
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