From: Vojtech Pavlik <vojtech@suse.cz>
To: Jiri Bohac <jbohac@suse.cz>
Cc: Andi Kleen <ak@suse.de>,
linux-kernel@vger.kernel.org, ssouhlal@freebsd.org,
arjan@infradead.org, tglx@linutronix.de, johnstul@us.ibm.com,
zippel@linux-m68k.org, andrea@suse.de
Subject: Re: [patch 4/9] Remove the TSC synchronization on SMP machines
Date: Thu, 1 Feb 2007 16:16:54 +0100 [thread overview]
Message-ID: <20070201151654.GA20385@suse.cz> (raw)
In-Reply-To: <20070201131715.GM21755@dwarf.suse.cz>
On Thu, Feb 01, 2007 at 02:17:15PM +0100, Jiri Bohac wrote:
> On Thu, Feb 01, 2007 at 12:14:23PM +0100, Andi Kleen wrote:
> > On Thursday 01 February 2007 10:59, jbohac@suse.cz wrote:
> > > TSC is either synchronized by design or not reliable
> > > to be used for anything, let alone timekeeping.
> >
> > In my tree this is already done better by a patch from Ingo.
> > Check if they look synchronized and don't use TSC if they are not.
>
> The whole purpose of this patchset is to make use of TSC even if
> it's not synchronized.
>
> Synchronizing it will not make anything better in any way -- the
> implementation just does not care whether TSCs are synchronized.
> That's why I think the synchronization code is not needed.
It might even make sense to desycnhronize the TSCs on such (AMD)
machines on purpose, so that applications that rely on TSC break
immediately and not after some time when the error becomes too large.
--
Vojtech Pavlik
Director SuSE Labs
next prev parent reply other threads:[~2007-02-01 15:17 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-01 9:59 [patch 0/9] x86_64: reliable TSC-based gettimeofday jbohac
2007-02-01 9:59 ` [patch 1/9] Fix HPET init race jbohac
2007-02-02 2:34 ` Andrew Morton
2007-02-06 16:44 ` Jiri Bohac
2007-02-07 0:12 ` Andrew Morton
2007-02-10 12:31 ` Andi Kleen
2007-07-26 20:58 ` Robin Holt
2007-02-01 9:59 ` [patch 2/9] Remove the support for the VXTIME_PMTMR timer mode jbohac
2007-02-01 11:13 ` Andi Kleen
2007-02-01 13:13 ` Jiri Bohac
2007-02-01 13:13 ` Andi Kleen
2007-02-01 13:59 ` Jiri Bohac
2007-02-01 14:18 ` Andi Kleen
2007-02-01 9:59 ` [patch 3/9] Remove the support for the VXTIME_HPET " jbohac
2007-02-01 9:59 ` [patch 4/9] Remove the TSC synchronization on SMP machines jbohac
2007-02-01 11:14 ` Andi Kleen
2007-02-01 13:17 ` Jiri Bohac
2007-02-01 15:16 ` Vojtech Pavlik [this message]
2007-02-02 7:14 ` Andi Kleen
2007-02-13 0:34 ` Christoph Lameter
2007-02-13 6:40 ` Arjan van de Ven
2007-02-13 8:28 ` Andi Kleen
2007-02-13 8:41 ` Arjan van de Ven
2007-02-13 17:09 ` Christoph Lameter
2007-02-13 17:20 ` Andi Kleen
2007-02-13 22:18 ` Vojtech Pavlik
2007-02-13 22:38 ` Andrea Arcangeli
2007-02-14 6:59 ` Vojtech Pavlik
2007-02-13 23:55 ` Christoph Lameter
2007-02-14 0:18 ` Paul Mackerras
2007-02-14 0:25 ` john stultz
2007-02-02 7:13 ` Andi Kleen
2007-02-01 21:05 ` mbligh
2007-02-03 1:16 ` H. Peter Anvin
2007-02-01 9:59 ` [patch 5/9] Add all the necessary structures to the vsyscall page jbohac
2007-02-01 11:17 ` Andi Kleen
2007-02-01 9:59 ` [patch 6/9] Add the "Master Timer" jbohac
2007-02-01 11:22 ` Andi Kleen
2007-02-01 13:29 ` Jiri Bohac
2007-02-01 9:59 ` [patch 7/9] Adapt the time initialization code jbohac
2007-02-01 11:26 ` Andi Kleen
2007-02-01 13:41 ` Jiri Bohac
2007-02-01 10:00 ` [patch 8/9] Add time_update_mt_guess() jbohac
2007-02-01 11:28 ` Andi Kleen
2007-02-01 13:54 ` Jiri Bohac
2007-02-01 10:00 ` [patch 9/9] Make use of the Master Timer jbohac
2007-02-01 11:36 ` Andi Kleen
2007-02-01 14:29 ` Jiri Bohac
2007-02-01 15:23 ` Vojtech Pavlik
2007-02-02 7:05 ` Andi Kleen
2007-02-02 7:04 ` Andi Kleen
2007-02-01 11:20 ` [patch 0/9] x86_64: reliable TSC-based gettimeofday Andi Kleen
2007-02-01 11:53 ` Andrea Arcangeli
2007-02-01 12:02 ` Andi Kleen
2007-02-01 12:54 ` Andrea Arcangeli
2007-02-01 12:17 ` Ingo Molnar
2007-02-01 14:52 ` Jiri Bohac
2007-02-01 16:56 ` john stultz
2007-02-01 19:41 ` Vojtech Pavlik
2007-02-01 11:34 ` Ingo Molnar
2007-02-01 11:46 ` [-mm patch] x86_64 GTOD: offer scalable vgettimeofday Ingo Molnar
2007-02-01 12:01 ` Andi Kleen
2007-02-01 12:14 ` Ingo Molnar
2007-02-01 12:17 ` [-mm patch] x86_64 GTOD: offer scalable vgettimeofday II Andi Kleen
2007-02-01 12:24 ` Ingo Molnar
2007-02-01 12:45 ` Andi Kleen
2007-02-02 4:22 ` [patch 0/9] x86_64: reliable TSC-based gettimeofday Andrew Morton
2007-02-02 7:07 ` Andi Kleen
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