From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752491AbcDJKEZ (ORCPT ); Sun, 10 Apr 2016 06:04:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:36332 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751413AbcDJKEY (ORCPT ); Sun, 10 Apr 2016 06:04:24 -0400 Message-ID: <1460282661.4251.44.camel@suse.de> Subject: Re: sched: tweak select_idle_sibling to look for idle threads From: Mike Galbraith To: Chris Mason , Peter Zijlstra , Ingo Molnar , Matt Fleming , linux-kernel@vger.kernel.org Date: Sun, 10 Apr 2016 12:04:21 +0200 In-Reply-To: <20160409190554.honue3gtian2p6vr@floor.thefacebook.com> References: <20160405180822.tjtyyc3qh4leflfj@floor.thefacebook.com> <20160409190554.honue3gtian2p6vr@floor.thefacebook.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2016-04-09 at 15:05 -0400, Chris Mason wrote: > This does preserve the existing logic to prefer idle cores over idle > CPU threads, and includes some tests to try and avoid the idle scan when we're > actually better off sharing a non-idle CPU with someone else. My box says the "oh nevermind" checks aren't selective enough, tbench dropped 4% at clients=cores, and 2% at clients=threads. > Benchmarks in production show overall capacity going up between 2-5% > depending on the metric. Latency rules all loads certainly exist, and clearly want some love, but the bigger the socket, and the more threads/core, the more that traverse is gonna hurt the others, so seems either we need a better filter, or a (yeah yeah, yet another damn) tweakable. Oh, and bounce_to_target() seems an odd way to say full_traverse. -Mike