From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755134Ab0IMTfp (ORCPT ); Mon, 13 Sep 2010 15:35:45 -0400 Received: from one.firstfloor.org ([213.235.205.2]:60577 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755049Ab0IMTfo (ORCPT ); Mon, 13 Sep 2010 15:35:44 -0400 From: Andi Kleen To: eranian@google.com Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@elte.hu, paulus@samba.org, davem@davemloft.net, fweisbec@gmail.com, perfmon2-devel@lists.sf.net, eranian@gmail.com, robert.richter@amd.com, markus.t.metzger@intel.com Subject: Re: [PATCH] perf_events: improve DS/BTS/PEBS buffer allocation References: <4c8e3c0c.12d1d80a.73d9.ffffcf21@mx.google.com> Date: Mon, 13 Sep 2010 21:35:39 +0200 In-Reply-To: <4c8e3c0c.12d1d80a.73d9.ffffcf21@mx.google.com> (Stephane Eranian's message of "Mon, 13 Sep 2010 16:55:01 +0200") Message-ID: <877hip4et0.fsf@basil.nowhere.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stephane Eranian writes: > The DS, BTS, and PEBS memory regions were allocated using kzalloc(), i.e., > requesting contiguous physical memory. There is no such restriction on > DS, PEBS and BTS buffers. Using kzalloc() could lead to error in case > no contiguous physical memory is available. BTS is requesting 64KB, > thus it can cause issues. PEBS is currently only requesting one page. > Both PEBS and BTS are static buffers allocated for each CPU at the > first user. When the last user exists, the buffers are released. DS supports page tables, but I have some doubts it really supports page faults. vmalloc today does page faults. I think the change is a good idea, but it will need vmalloc_sync_all() everywhere. -Andi -- ak@linux.intel.com -- Speaking for myself only.