Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753826AbZFXIaX (ORCPT ); Wed, 24 Jun 2009 04:30:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751338AbZFXIaI (ORCPT ); Wed, 24 Jun 2009 04:30:08 -0400 Received: from nox.protox.org ([88.191.38.29]:53269 "EHLO nox.protox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751301AbZFXIaG (ORCPT ); Wed, 24 Jun 2009 04:30:06 -0400 Subject: Re: [PATCH] radeon: preallocate memory for command stream parsing From: Jerome Glisse To: Pekka Enberg Cc: Jerome Glisse , Nick Piggin , Christoph Lameter , linux-kernel@vger.kernel.org, dri-devel@lists.sf.net In-Reply-To: <84144f020906231252u5131ffbdk74f06f8a0f692cf9@mail.gmail.com> References: <1245786367-2773-1-git-send-email-jglisse@redhat.com> <84144f020906231252u5131ffbdk74f06f8a0f692cf9@mail.gmail.com> Content-Type: text/plain Date: Wed, 24 Jun 2009 10:29:01 +0200 Message-Id: <1245832141.2408.4.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.26.2 (2.26.2-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1377 Lines: 34 On Tue, 2009-06-23 at 22:52 +0300, Pekka Enberg wrote: > Hi Jerome, > > On Tue, Jun 23, 2009 at 10:46 PM, Jerome Glisse wrote: > > Command stream parsing is the most common operation and can > > happen hundred of times per second, we don't want to allocate/free > > memory each time this ioctl is call. This rework the ioctl > > to avoid doing so by allocating temporary memory along the > > ib pool. > > > > Signed-off-by: Jerome Glisse > > So how much does this help (i.e. where are the numbers)? I am bit > surprised "hundred of times per second" is an issue for our slab > allocators. Hmm? > I didn't have real number but the vmap path was really slower, quake3 fps goes from ~20 to ~40 on average when going from vmap to preallocated. When using kmalloc i don't thing there was so much performance hit. But i think the biggest hit was that in previous code i asked for zeroed memory so i am pretty sure kernel spend a bit of time clearing page. I reworked the code to avoid needing cleared memory and so avoid memset, this is likely why we get a performance boost. Cheers, Jerome -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/