From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751760AbcFWSdW (ORCPT ); Thu, 23 Jun 2016 14:33:22 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49587 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751166AbcFWSdV (ORCPT ); Thu, 23 Jun 2016 14:33:21 -0400 Date: Thu, 23 Jun 2016 20:33:18 +0200 From: Peter Zijlstra To: Jirka Hladky Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Kamil Kolakowski Subject: Re: Kernel 4.7rc3 - Performance drop 30-40% for SPECjbb2005 and SPECjvm2008 benchmarks against 4.6 kernel Message-ID: <20160623183318.GN30154@twins.programming.kicks-ass.net> References: <20160616172256.GJ30921@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 17, 2016 at 01:04:23AM +0200, Jirka Hladky wrote: > > What kind of config and userspace setup? Do you run this cruft in a > > cgroup of sorts? > > No, we don't do any special setup except to control the number of threads. OK, so I'm fairly certain you _do_ run in a cgroup, because its made almost impossible not to these days. Run: grep java /proc/sched_debug while the thing is running. That'll show you the actual cgroup the stuff is running in. This modern Linux stuff stinks loads. And even Debian seems infected to the point of almost being useless :-( The _only_ reason I could reproduce was because I recently did an upgrade of Debian Testing and I hadn't noticed just how messed up things had become. When I run it in the root cgroup (I had to kill cgmanager and reboot) the numbers are just fine. In any case, now I gotta go look at the cgroup code...