From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757141AbZIRRWR (ORCPT ); Fri, 18 Sep 2009 13:22:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756246AbZIRRWR (ORCPT ); Fri, 18 Sep 2009 13:22:17 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:53889 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756449AbZIRRWQ (ORCPT ); Fri, 18 Sep 2009 13:22:16 -0400 Date: Fri, 18 Sep 2009 10:22:34 -0700 (PDT) Message-Id: <20090918.102234.175792545.davem@davemloft.net> To: a.p.zijlstra@chello.nl Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, jens.axboe@oracle.com Subject: Re: [PATCH 0/2]: Get perf counters working on D-cache aliasing cpus. From: David Miller In-Reply-To: <1253277096.8439.127.camel@twins> References: <20090908.051045.26522683.davem@davemloft.net> <1253277096.8439.127.camel@twins> X-Mailer: Mew version 6.2.51 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra Date: Fri, 18 Sep 2009 14:31:36 +0200 > Ingo just reminded me that we might want to do splice support for perf > stuff. My plan was to have the splice thing allocate a new page, flip > with a filled one from the buffer and send the filled one down to the > splice consumer. > > Now having vmap'ed all that complicates stuff enourmously. > > Would it also work if we use order-1 pages on your platform instead of > order-0, so that they are properly aligned for the d-cache? You still have to make sure the order-1 page is order-1 virtually aligned in userspace. But that would help only sparc64 because SHMLBA happens to be 16K (2 * smallest supported PAGE_SIZE). So, this won't handle sparc32 where the SHMLBA is 4MB. MIPS has the same exact problems and has a large SHMLBA too.