From: Robin Holt <holt@sgi.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: holt@sgi.com, Ingo Molnar <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Venkatesh Pallipadi <venkatesh.pallipadi@gmail.com>,
Suresh Siddha <suresh.b.siddha@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
x86@kernel.org, Rafael Wysocki <rjw@novell.com>
Subject: Re: [patch 0/2] x86,pat: Reduce contention on the memtype_lock -V4
Date: Wed, 24 Mar 2010 03:55:11 -0500 [thread overview]
Message-ID: <20100324085511.GJ4920@sgi.com> (raw)
In-Reply-To: <87wrx2for5.fsf@basil.nowhere.org>
On Wed, Mar 24, 2010 at 03:16:14AM +0100, Andi Kleen wrote:
> holt@sgi.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.
It was a job using xpmem (an out of tree kernel module) which uses
vm_insert_pfn to establish ptes. The scalability issues were shown
in the first patch. I do not have any test which shows a performance
difference with the spin_lock to rw_lock conversion.
Robin
next prev parent reply other threads:[~2010-03-24 8:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-24 0:36 [patch 0/2] x86,pat: Reduce contention on the memtype_lock -V4 holt
2010-03-24 0:36 ` [patch 1/2] x86,pat Update the page flags for memtype atomically instead of using memtype_lock. -V4 holt
2010-03-24 0:36 ` [patch 2/2] x86,pat Convert memtype_lock into an rw_lock holt
2010-03-24 2:16 ` [patch 0/2] x86,pat: Reduce contention on the memtype_lock -V4 Andi Kleen
2010-03-24 8:55 ` Robin Holt [this message]
2010-03-24 11:15 ` Thomas Gleixner
2010-03-24 16:22 ` Suresh Siddha
2010-03-24 20:32 ` Rafael J. Wysocki
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