From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754336Ab1LLWQD (ORCPT ); Mon, 12 Dec 2011 17:16:03 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:51263 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754185Ab1LLWQA (ORCPT ); Mon, 12 Dec 2011 17:16:00 -0500 Message-ID: <4EE67CB5.7000404@fb.com> Date: Mon, 12 Dec 2011 14:14:13 -0800 From: Arun Sharma User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:8.0) Gecko/20111105 Thunderbird/8.0 MIME-Version: 1.0 To: Eric Dumazet CC: , Kumar Sundararajan , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , john stultz , Andy Lutomirski Subject: Re: [PATCH 2/2] Add a thread cpu time implementation to vDSO References: <1323718578-1157-1-git-send-email-asharma@fb.com> <1323718578-1157-3-git-send-email-asharma@fb.com> <1323720791.2583.23.camel@edumazet-laptop> <4EE66FE9.1050202@fb.com> <1323725243.2583.27.camel@edumazet-laptop> In-Reply-To: <1323725243.2583.27.camel@edumazet-laptop> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.18.252] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.5.7110,1.0.211,0.0.0000 definitions=2011-12-12_10:2011-12-12,2011-12-12,1970-01-01 signatures=0 X-Proofpoint-Spam-Reason: safe Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12/11 1:27 PM, Eric Dumazet wrote: > This only works if CONFIG_X86_L1_CACHE_SHIFT=6 > > Some configurations have 128 bytes cache lines > I could still handle this case based on compile time math. > But really most modern distros have NR_CPUS> 64 Is 256 the new 64? :) That'll require 3 more VVAR pages, most of which would be unused on the vast majority of the systems (assuming 32 CPUs or less). Having the number of VVAR pages configurable at boot time would solve this problem nicely. I think that should be a separate patch. -Arun