From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933129Ab2GYN5y (ORCPT ); Wed, 25 Jul 2012 09:57:54 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:51601 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S933048Ab2GYN5w (ORCPT ); Wed, 25 Jul 2012 09:57:52 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX19S6ylFoCxSOxnQdYNVH9tlkiksAEYz5J/Ewzoefi QRIZr4TRD7E/zt Message-ID: <1343224667.5745.67.camel@marge.simpson.net> Subject: Re: Attaching a process to cgroups From: Mike Galbraith To: Alexey Vlasov Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com Date: Wed, 25 Jul 2012 15:57:47 +0200 In-Reply-To: <20120725133637.GA9169@beaver> References: <20120619185856.GC31797@beaver> <1340195298.15707.3.camel@marge.simpson.net> <20120725133637.GA9169@beaver> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2012-07-25 at 17:36 +0400, Alexey Vlasov wrote: > Hi. > > Now I've got almost 5k used groups and it got even worse. Now I've got > almost 5k used groups and it got even worse. > > If only write was working slower, now everything connected with cgroups > is hardly working. > > Could it be connected with synchronize_rcu()? I'd profile it with perf, and expect to find a large pile of cycles. > Hanging on read(): > > # strace -ttT cat /proc/cgroups > > 17:30:43.825005 fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 13), ...}) = 0 <0.000005> > 17:30:43.825048 open("/proc/cgroups", O_RDONLY) = 3 <0.000014> > 17:30:43.825085 fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 <0.000004> > 17:30:43.825125 fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0 <0.000005> > 17:30:43.825161 read(3, "#subsys_name\thierarchy\tnum_cgrou"..., 32768) = 112 <7.447084> Ew.. zillion cgroups is definitely a bad idea. -Mike