From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753113Ab0IMPzv (ORCPT ); Mon, 13 Sep 2010 11:55:51 -0400 Received: from smtp-out.google.com ([216.239.44.51]:10989 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920Ab0IMPzt convert rfc822-to-8bit (ORCPT ); Mon, 13 Sep 2010 11:55:49 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=PVVNC1melHInmhZf/Y1IEXoLXeEgbcrrAXHY5EUa005vX0Kmj2lgt05zd5vsP5NTjy OawxOEZUSB/CZKqu1cTA== MIME-Version: 1.0 In-Reply-To: <1284392476.2275.369.camel@laptop> References: <4c8e3c0c.12d1d80a.73d9.ffffcf21@mx.google.com> <20100913150914.GA6155@nowhere> <1284391000.2275.338.camel@laptop> <1284391480.2275.350.camel@laptop> <1284392476.2275.369.camel@laptop> Date: Mon, 13 Sep 2010 17:55:43 +0200 Message-ID: Subject: Re: [PATCH] perf_events: improve DS/BTS/PEBS buffer allocation From: Stephane Eranian To: Peter Zijlstra Cc: Frederic Weisbecker , Mathieu Desnoyers , linux-kernel@vger.kernel.org, mingo@elte.hu, paulus@samba.org, davem@davemloft.net, perfmon2-devel@lists.sf.net, eranian@gmail.com, robert.richter@amd.com, "markus.t.metzger" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 13, 2010 at 5:41 PM, Peter Zijlstra wrote: > On Mon, 2010-09-13 at 17:31 +0200, Stephane Eranian wrote: >> On Mon, Sep 13, 2010 at 5:24 PM, Peter Zijlstra wrote: >> > On Mon, 2010-09-13 at 17:20 +0200, Stephane Eranian wrote: >> > >> >> That is the case we the sizes you have chosen today. For DS, we >> >> could round up to one page for now. >> > >> > Markus chose the BTS size, for PEBS a single page was plenty since we do >> > single event things (although we could do multiple for attr.precise_ip < >> > 2). >> > >> > For DS there's: >> >  kmalloc_node(sizeof(struct ds), GFP_KERNEL | __GFP_ZERO, cpu_node(cpu)); >> > >> Ok, let try again with alloc_pages_node() + kmalloc_node(). >> I think we can stick with kmalloc() for DS because we are far from >> consuming a page. > > Thing is, if you're really seeing allocation failures, > alloc_pages_node() isn't going to help. And the problem is, these > allocations aren't movable, so memory compaction and all the other fancy > stuff aren't really going to help much :/ > Ok, so you're saying there is no allocator that will give non-contiguous physical memory WITHOUT requiring a page fault to populate the pte. On the other hand, with vmalloc_node() the pte are populated when you first touch the memory. That happens as part of memset() right after the allocation and thus outside of NMI interrupt handler. Does this sound right? > There was some talk about a function that should sync all of vmalloc > space, but iirc it was broken for some configs. >