From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: Re: Even faster page copy for Xen? Date: Tue, 10 Aug 2010 07:24:13 +0100 Message-ID: <4C610CAD020000780000EF6A@vpn.id2.novell.com> References: <4C5BDC79020000780000E9AB@vpn.id2.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dulloor Cc: Dan Magenheimer , xen-devel@lists.xensource.com, Keir Fraser List-Id: xen-devel@lists.xenproject.org >>> On 09.08.10 at 19:57, Dulloor wrote: > On Mon, Aug 9, 2010 at 10:47 AM, Dulloor wrote: >> On Fri, Aug 6, 2010 at 12:57 AM, Jan Beulich = wrote: >>> I'm not sure how much of this applies to the much more specific >>> case of copying pages... Additionally, I don't think trying to >>> use XMM registers in Xen would be a good idea. >=20 >> Why would you say using xmm/sse in Xen is a bad idea ? We already have = a >> copy_page_sse2 (in copy_page.S) in our code base and available (by = default) >> for x86_64. Is it a bad idea to use that ? >=20 > Never mind about copy_page_sse2 ! That function name is misleading. Why - it is code that's dependent on SSE2 to be available. Note it doesn't have 'xmm' in its name - that indeed would be misleading. > But, still ... I need a copy_page routine and was planning to use sse. > Is that not fine ? You can do so if you feel like saving/restoring all necessary XMM state isn't going to eat up all of the performance win... Jan