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From: Arjan van de Ven <arjan@linux.intel.com>
To: Thomas Renninger <trenn@suse.de>
Cc: "Luis R. Rodriguez" <lrodriguez@atheros.com>,
	davej@redhat.com, cpufreq@vger.kernel.org,
	linux-kernel@vger.kernel.org, mcgrof@gmail.com,
	Matthew Garrett <mjg@redhat.com>,
	Reinette Chatre <reinette.chatre@intel.com>,
	Aeolus Yang <Aeolus.Yang@atheros.com>,
	Amod Bodas <Amod.Bodas@atheros.com>,
	David Quan <David.Quan@atheros.com>,
	Kishore Jotwani <Kishore.Jotwani@atheros.com>
Subject: Re: [PATCH] cpu-freq: add troubleshooting section for FSB changes
Date: Sat, 07 Nov 2009 16:59:19 -0600	[thread overview]
Message-ID: <4AF5FBC7.9000105@linux.intel.com> (raw)
In-Reply-To: <200911072347.05786.trenn@suse.de>

>> in addition, most FSB systems have the memory controller in the chipset,
>> next to the PCI logic... so that the FSB bus for DMA transactions only
>> carries the snoop traffic, not the whole data.
> So when should people look at this?

at this point the atheros folks haven't even confirmed that this is the cause...

I'm not saying that the linux behavior is optimal with P states (I have a rather
sizeable algorithm rewrite in the queue) but to blame anything and everything on
a half-speed FSB during a very idle system?
I'm still somewhat skeptical. Again.. the CPU is basically idle here (otherwise
ondemand would ramp the freq up quickly); at which point the FSB traffic mostly is
just cache coherency traffic.... much less bandwidth intensive.

  reply	other threads:[~2009-11-07 22:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-06 20:01 [PATCH] cpu-freq: add troubleshooting section for FSB changes Luis R. Rodriguez
2009-11-07 20:52 ` Thomas Renninger
2009-11-07 21:10   ` Thomas Renninger
2009-11-07 22:28   ` Arjan van de Ven
2009-11-07 22:47     ` Thomas Renninger
2009-11-07 22:59       ` Arjan van de Ven [this message]
2009-11-08  0:54         ` Matthew Garrett
2009-11-09 16:32         ` Luis R. Rodriguez
2009-11-10 12:12           ` Corrado Zoccolo
2009-11-13 17:18             ` Luis R. Rodriguez

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