From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751772AbaEZH4b (ORCPT ); Mon, 26 May 2014 03:56:31 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:65446 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751185AbaEZH4a (ORCPT ); Mon, 26 May 2014 03:56:30 -0400 Message-ID: <1401090987.5339.79.camel@marge.simpson.net> Subject: Re: balance storm From: Mike Galbraith To: Libo Chen Cc: tglx@linutronix.de, mingo@elte.hu, LKML , Greg KH , Li Zefan Date: Mon, 26 May 2014 09:56:27 +0200 In-Reply-To: <5382AF2E.1040407@huawei.com> References: <5382AF2E.1040407@huawei.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2014-05-26 at 11:04 +0800, Libo Chen wrote: > hi, > my box has 16 cpu (E5-2658,8 core, 2 thread per core), i did a test on > 3.4.24stable, startup 50 same process, every process is sample: > > #include > > int main() > { > for (;;) > { > unsigned int i = 0; > while (i< 100){ > i++; > } > usleep(100); > } > > return 0; > } > > the result is process uses 15% cpu time, perf tool shows 70w migrations in 5 second. My 8 socket 64 core DL980 running 256 copies (3.14-rt5) munches ~4%/copy per top, and does roughly 1 sh*tload migrations, nano-work loop or not. Turn SD_SHARE_PKG_RESOURCES off at MC (not a noop here), and consumption drops to ~2%/copy, and migrations ('course) mostly go away. vogelweide:/abuild/mike/:[0]# perf stat -a -e sched:sched_migrate_task -- sleep 5 Performance counter stats for 'system wide': 3108 sched:sched_migrate_task 5.001367910 seconds time elapsed (turns SD_SHARE_PKG_RESOURCES back on) vogelweide:/abuild/mike/:[0]# perf stat -a -e sched:sched_migrate_task -- sleep 5 Performance counter stats for 'system wide': 4182334 sched:sched_migrate_task 5.001365023 seconds time elapsed vogelweide:/abuild/mike/:[0]#