From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941448AbcJXTDy (ORCPT ); Mon, 24 Oct 2016 15:03:54 -0400 Received: from mx2.suse.de ([195.135.220.15]:33697 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941431AbcJXTDv (ORCPT ); Mon, 24 Oct 2016 15:03:51 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 24 Oct 2016 11:50:50 -0700 From: Davidlohr Bueso To: Arnaldo Carvalho de Melo Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Sebastian Andrzej Siewior , Peter Zijlstra , Arnaldo Carvalho de Melo Subject: Re: [PATCH 33/37] perf bench futex: Cache align the worker struct Organization: SUSE Labs In-Reply-To: <1477326057-24080-34-git-send-email-acme@kernel.org> References: <1477326057-24080-1-git-send-email-acme@kernel.org> <1477326057-24080-34-git-send-email-acme@kernel.org> Message-ID: <94c3f945b1f11c799d4ec4ab5a0efc90@suse.de> User-Agent: Roundcube Webmail Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016-10-24 09:20, Arnaldo Carvalho de Melo wrote: > From: Sebastian Andrzej Siewior > > It popped up in perf testing that the worker consumes some amount of > CPU. It boils down to the increment of `ops` which causes cache line > bouncing between the individual threads. > > This patch aligns the struct by 256 bytes to ensure that not a cache > line is shared among CPUs. 128 byte is the x86 worst case and grep says > that L1_CACHE_SHIFT is set to 8 on s390. Hmm so this one should have been replaced with this: https://marc.info/?l=linux-kernel&m=147690008801082 Thanks, Davidlohr