From: Suresh Siddha <suresh.b.siddha@intel.com>
To: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>, H Peter Anvin <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: Reenable TSC sync check at boot, even with NONSTOP_TSC
Date: Thu, 17 Dec 2009 13:00:23 -0800 [thread overview]
Message-ID: <1261083624.2535.299.camel@sbs-t61> (raw)
In-Reply-To: <20091217202702.GA18015@linux-os.sc.intel.com>
On Thu, 2009-12-17 at 13:27 -0700, Pallipadi, Venkatesh wrote:
> Commit 83ce4009 did the following change
> If the TSC is constant and non-stop, also set it reliable.
>
> But, there seems to be few systems that will end up with TSC warp across
> sockets, depending on how the cpus come out of reset. Skipping TSC sync
> test on such systems may result in time inconsistency later.
>
> So, reenable TSC sync test even on constant and non-stop TSC systems.
> Set, sched_clock_stable to 1 by default and reset it in
> mark_tsc_unstable, if TSC sync fails.
>
> This change still gives perf benefit mentioned in 83ce4009 for systems
> where TSC is reliable.
>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
next prev parent reply other threads:[~2009-12-17 21:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-17 20:27 [PATCH] x86: Reenable TSC sync check at boot, even with NONSTOP_TSC Pallipadi, Venkatesh
2009-12-17 21:00 ` Suresh Siddha [this message]
2009-12-17 23:57 ` [tip:x86/urgent] " tip-bot for Pallipadi, Venkatesh
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