From: Joerg Roedel <joro@8bytes.org>
To: Mark Langsdorf <mark.langsdorf@amd.com>
Cc: linux-kernel@vger.kernel.org, bhavna.sarathy@amd.com, davej@redhat.com
Subject: Re: [PATCH] Option to synchronize P-states for AMD family 0xf
Date: Wed, 30 Sep 2009 12:00:59 +0200 [thread overview]
Message-ID: <20090930100059.GG29634@8bytes.org> (raw)
In-Reply-To: <200909291623.56130.mark.langsdorf@amd.com>
On Tue, Sep 29, 2009 at 04:23:55PM -0500, Mark Langsdorf wrote:
> AMD Family 0xf processors (Athlon 64s and Opterons) do not
> have P-State or C-State invariant TSCs. Instead, the TSC
> increments at the current processor frequency, which makes
> it unstable and unreliable if cpufreq is enabled.
>
> This patch introduces a new command parameter for the
> PowerNow! driver called "tscsync". When tscsync is
> set to 1, the driver forces all processors in the system
> to change frequency as the same time to the same frequency.
> This unified change means that all the TSCs in the system
> increment at the same rate.
Cool feature. Does Linux consider the TSC as stable on these machines
even after a longer uptime (say after a week)?
Joerg
next prev parent reply other threads:[~2009-09-30 10:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-29 21:23 [PATCH] Option to synchronize P-states for AMD family 0xf Mark Langsdorf
2009-09-30 10:00 ` Joerg Roedel [this message]
2009-09-30 14:30 ` Langsdorf, Mark
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