From: Suresh Siddha <suresh.b.siddha@intel.com>
To: "holt@sgi.com" <holt@sgi.com>
Cc: Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
Venkatesh Pallipadi <venkatesh.pallipadi@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [patch 1/2] x86,pat Update the page flags for memtype atomically instead of using memtype_lock. -V3
Date: Wed, 17 Mar 2010 08:21:16 -0800 [thread overview]
Message-ID: <1268842876.2696.9.camel@sbs-t61> (raw)
In-Reply-To: <20100315132110.688234145@gulag1.americas.sgi.com>
On Mon, 2010-03-15 at 06:21 -0700, holt@sgi.com wrote:
> While testing an application using the xpmem (out of kernel) driver, we
> noticed a significant page fault rate reduction of x86_64 with respect
> to ia64. For one test running with 32 cpus, one thread per cpu, it
> took 01:08 for each of the threads to vm_insert_pfn 2GB worth of pages.
> For the same test running on 256 cpus, one thread per cpu, it took 14:48
> to vm_insert_pfn 2 GB worth of pages.
>
> The slowdown was tracked to lookup_memtype which acquires the
> spinlock memtype_lock. This heavily contended lock was slowing down
> vm_insert_pfn().
>
> With the cmpxchg on page->flags method, both the 32 cpu and 256 cpu
> cases take approx 00:01.3 seconds to complete.
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
next prev parent reply other threads:[~2010-03-17 15:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-15 13:21 [patch 0/2] x86,pat: Reduce contention on the memtype_lock -V3 holt
2010-03-15 13:21 ` [patch 1/2] x86,pat Update the page flags for memtype atomically instead of using memtype_lock. -V3 holt
2010-03-17 10:18 ` Robin Holt
2010-03-17 16:21 ` Suresh Siddha [this message]
2010-03-23 23:21 ` Rafael J. Wysocki
2010-03-15 13:21 ` [patch 2/2] x86,pat Convert memtype_lock into an rw_lock holt
2010-03-17 16:21 ` Suresh Siddha
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