From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Zachary Amsden <zach@vmware.com>
Cc: Andrew Morton <akpm@osdl.org>, Andi Kleen <ak@muc.de>,
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 1/4] Pte drop ptep_get_and_clear paravirt op.patch
Date: Tue, 17 Apr 2007 09:32:44 -0400 [thread overview]
Message-ID: <4624CC7C.6040107@goop.org> (raw)
In-Reply-To: <200704120530.l3C5Ubs0022821@zach-dev.vmware.com>
Zachary Amsden wrote:
> In shadow mode hypervisors, ptep_get_and_clear achieves the desired
> purpose of keeping the shadows in sync by issuing a native_get_and_clear,
> followed by a call to pte_update, which indicates the PTE has been
> modified.
>
> Direct mode hypervisors (Xen) have no need for this anyway, and will trap
> the update using writable pagetables.
>
Jan Beulich just posted a patch for Xen/linux which specialzes
ptep_get_and_clear, which apparently improves kernel-compile performance
by 25-30% on some configurations. I think we'll want to keep this.
J
next prev parent reply other threads:[~2007-04-17 13:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-12 5:30 [PATCH 1/4] Pte drop ptep_get_and_clear paravirt op.patch Zachary Amsden
2007-04-12 19:48 ` Jeremy Fitzhardinge
2007-04-12 19:47 ` Zachary Amsden
2007-04-17 13:32 ` Jeremy Fitzhardinge [this message]
2007-04-17 11:18 ` Zachary Amsden
2007-04-18 13:05 ` Jeremy Fitzhardinge
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