From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758633Ab3J2Rcg (ORCPT ); Tue, 29 Oct 2013 13:32:36 -0400 Received: from mail-oa0-f47.google.com ([209.85.219.47]:57476 "EHLO mail-oa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758258Ab3J2Rcf (ORCPT ); Tue, 29 Oct 2013 13:32:35 -0400 Message-ID: <526FF131.3070105@linaro.org> Date: Tue, 29 Oct 2013 10:32:33 -0700 From: Daniel Lezcano User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Linux Kernel Mailing List , Peter Zijlstra CC: Ingo Molnar Subject: [Question] : tie a task to a cluster when it shares memory resources Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, I am not expert on the NUMA area and the scheduler but I was wondering the following: On numa a process can define a memory policy to optimize access because remote memory access is suboptimal. On a multicluster (aka multipackage), eg. Bi-Xeon 4 cores, the scheduler load balancing can spawn/balance a task to the second cluster even if the task is resulting from a fork or a pthread_create. If I am correct that could impact the performances due to L2 cache misses, no ? Won't it be more efficient to tie a task to a cluster when it shares memory resources with another task on the same cluster ? and when the task does 'exec', this constraint is removed. Thanks -- Daniel -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog