linux-kernel - Re: [patch 0/2] x86,pat: Reduce contention on the memtype

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Date:	Wed, 24 Mar 2010 03:16:14 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	holt@....com
Cc:	Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...il.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	x86@...nel.org, Rafael Wysocki <rjw@...ell.com>
Subject: Re: [patch 0/2] x86,pat: Reduce contention on the memtype_lock -V4

holt@....com writes:

> Tracking memtype on x86 uses a single global spin_lock for either reading
> or changing the memory type.  This includes changes made to page flags
> which is perfectly parallel.
>
> Part one of the patchset makes the page-based tracking use cmpxchg
> without a need for a lock.
>
> Part two of the patchset converts the spin_lock into a read/write lock.

I'm curious: in what workloads did you see contention?

For any scalability patches it would be always good to have a description
of the workload.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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