From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754639Ab0IMUfc (ORCPT ); Mon, 13 Sep 2010 16:35:32 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52400 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751495Ab0IMUfb (ORCPT ); Mon, 13 Sep 2010 16:35:31 -0400 Message-ID: <4C8E8ABF.605@zytor.com> Date: Mon, 13 Sep 2010 13:34:07 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.8) Gecko/20100806 Fedora/3.1.2-1.fc13 Thunderbird/3.1.2 MIME-Version: 1.0 To: Andi Kleen CC: eranian@google.com, 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> <877hip4et0.fsf@basil.nowhere.org> In-Reply-To: <877hip4et0.fsf@basil.nowhere.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/13/2010 12:35 PM, Andi Kleen wrote: > > DS supports page tables, but I have some doubts it really > supports page faults. vmalloc today does page faults. > It specifically does not (SDM III 16.4.9.2). In fact, it requires that the pages be mapped Accessed and Dirty so the hardware doesn't have to stop and set those bits. The options thus are vmalloc_sync_all(), which will make Linus unhappy (since he seems to want to get rid of the thing), or doing fixmap-style reserved address space which is always consistent because the PDEs are preallocated and frozen. -hpa