From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Kcqoj-0004TX-HG for qemu-devel@nongnu.org; Mon, 08 Sep 2008 20:10:49 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Kcqog-0004RO-RG for qemu-devel@nongnu.org; Mon, 08 Sep 2008 20:10:49 -0400 Received: from [199.232.76.173] (port=60333 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Kcqog-0004R6-M7 for qemu-devel@nongnu.org; Mon, 08 Sep 2008 20:10:46 -0400 Received: from mail2.shareable.org ([80.68.89.115]:40620) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Kcqog-0006U4-Ad for qemu-devel@nongnu.org; Mon, 08 Sep 2008 20:10:46 -0400 Date: Tue, 9 Sep 2008 01:10:44 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] [PATCH] opengl rendering in the sdl window Message-ID: <20080909001044.GA18018@shareable.org> References: <48C16207.5090808@eu.citrix.com> <20080905165536.GA12606@redhat.com> <48C168CE.5040700@eu.citrix.com> <48C348D3.6070702@codemonkey.ws> <20080908134140.GF4947@shareable.org> <20080908134833.GQ2315@redhat.com> <48C53D24.8030803@redhat.com> <20080908150759.GB8465@shareable.org> <20080908154700.GT2315@redhat.com> <20080908231843.GA29606@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080908231843.GA29606@redhat.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: qemu-devel@nongnu.org Daniel P. Berrange wrote: > Just thought I'd mention one other thing - it is not actually clearcut / or > guarenteed that XShm + VNC would improve performance in all circumstances. > This is because X pixmaps created via XShm apparently cannot live in video > memory, and thus it is not so easy to get full performance advantage of > hardware acceleration - this could impact scaling for example. I haven't seen any scaling with VNC so far, but it would be nice sometimes. How does sending the image over the wire then asking the server to scale it using RENDER improve on sending it over XShm then asking the server to xscale the pixel using RENDER? Or is there something else you can do when you don't use XShm? > The need to > perform XSync operations when updating the pixmaps may also negate the > benefit of avoiding the socket I/O. You don't have to do XSync, if you don't mind a bit of tearing which you're probably going to get anyway, or if you do some fancy locking until you receive XShmCompletionEvent asynchronously and the blit is fast. Or you can double-buffer or triple-buffer with multiple XShm pixmaps; I don't know how that compares with sending the image over the socket. Or you can do both: switch to a new buffer only when the guest writes to video memory before receiving XShmCopmletionEvent, otherwise stay with the old buffer. -- Jamie