From: Dave Jones <davej@redhat.com>
To: Zachary Amsden <zach@vmware.com>
Cc: Andrew Morton <akpm@osdl.org>, Andi Kleen <ak@muc.de>,
Virtualization Mailing List <virtualization@lists.osdl.org>,
Chris Wright <chrisw@sous-sol.org>,
David Rientjes <rientjes@google.com>,
Hugh Dickins <hugh@veritas.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/4] Pte xchg optimization.patch
Date: Thu, 12 Apr 2007 14:18:09 -0400 [thread overview]
Message-ID: <20070412181809.GC25646@redhat.com> (raw)
In-Reply-To: <200704120530.l3C5UweV022834@zach-dev.vmware.com>
On Wed, Apr 11, 2007 at 10:30:58PM -0700, Zachary Amsden wrote:
> In situations where page table updates need only be made locally, and there
> is no cross-processor A/D bit races involved, we need not use the heavyweight
> xchg instruction to atomically fetch and clear page table entries. Instead,
> we can just read and clear them directly.
>
> This introduces a neat optimization for non-SMP kernels; drop the atomic
> xchg operations from page table updates.
Would it be feasible to do this using the smp_alternatives stuff?
Given many distros are now shipping SMP-only kernels, it'd be nice
to get that win without using having to rebuild their kernels.
Dave
--
http://www.codemonkey.org.uk
WARNING: multiple messages have this Message-ID (diff)
From: Dave Jones <davej@redhat.com>
To: Zachary Amsden <zach@vmware.com>
Cc: Andrew Morton <akpm@osdl.org>, Andi Kleen <ak@muc.de>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Rusty Russell <rusty@rustcorp.com.au>,
Chris Wright <chrisw@sous-sol.org>,
Hugh Dickins <hugh@veritas.com>,
David Rientjes <rientjes@google.com>,
Michel Lespinasse <walken@vmware.com>,
Virtualization Mailing List <virtualization@lists.osdl.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/4] Pte xchg optimization.patch
Date: Thu, 12 Apr 2007 14:18:09 -0400 [thread overview]
Message-ID: <20070412181809.GC25646@redhat.com> (raw)
In-Reply-To: <200704120530.l3C5UweV022834@zach-dev.vmware.com>
On Wed, Apr 11, 2007 at 10:30:58PM -0700, Zachary Amsden wrote:
> In situations where page table updates need only be made locally, and there
> is no cross-processor A/D bit races involved, we need not use the heavyweight
> xchg instruction to atomically fetch and clear page table entries. Instead,
> we can just read and clear them directly.
>
> This introduces a neat optimization for non-SMP kernels; drop the atomic
> xchg operations from page table updates.
Would it be feasible to do this using the smp_alternatives stuff?
Given many distros are now shipping SMP-only kernels, it'd be nice
to get that win without using having to rebuild their kernels.
Dave
--
http://www.codemonkey.org.uk
next prev parent reply other threads:[~2007-04-12 18:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-12 5:30 [PATCH 3/4] Pte xchg optimization.patch Zachary Amsden
2007-04-12 18:18 ` Dave Jones [this message]
2007-04-12 18:18 ` Dave Jones
2007-04-12 18:44 ` Zachary Amsden
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