Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754275Ab1DGJ4E (ORCPT ); Thu, 7 Apr 2011 05:56:04 -0400 Received: from mailout-de.gmx.net ([213.165.64.22]:50236 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751827Ab1DGJ4D (ORCPT ); Thu, 7 Apr 2011 05:56:03 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1/UYYk4Gl/UMUhwbRr8zXCQSuu/rSGIoxqiVZUoI5 dtYVULpXQ+MUfq Subject: query: [PATCH 2/2] cgroup: Remove call to synchronize_rcu in cgroup_attach_task From: Mike Galbraith To: LKML Cc: Paul Menage , Colin Cross , Peter Zijlstra , Ingo Molnar , Li Zefan Content-Type: text/plain; charset="UTF-8" Date: Thu, 07 Apr 2011 11:55:53 +0200 Message-ID: <1302170153.12304.31.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2963 Lines: 74 Greetings, Wrt these patches: https://lkml.org/lkml/2010/11/24/14 [PATCH 1/2] cgroup: Set CGRP_RELEASABLE when adding to a cgroup https://lkml.org/lkml/2010/11/24/15 [PATCH 2/2] cgroup: Remove call to synchronize_rcu in cgroup_attach_task I received a query regarding 2/2 because a large database company is apparently moving tasks between cgroups frequently enough that their database initialization time dropped from ~11 hours to ~4 hours when they applied this patch. Curious why these got no traction. Regardless of the wisdom of frequent cgroup moves, Joe User launching light tasks via cgexec would gain quite a bit as well it seems. Q/D measurement of cgexec -g cpu:test sh -c exit. Unpatched: marge:~ # time perf stat --repeat=1000 cgexec -g cpu:test sh -c exit Performance counter stats for 'cgexec -g cpu:test sh -c exit' (1000 runs): 2.686149 task-clock-msecs # 0.119 CPUs ( +- 0.067% ) 2 context-switches # 0.001 M/sec ( +- 0.100% ) 0 CPU-migrations # 0.000 M/sec ( +- 35.231% ) 633 page-faults # 0.236 M/sec ( +- 0.003% ) 6292755 cycles # 2342.668 M/sec ( +- 0.062% ) 4844702 instructions # 0.770 IPC ( +- 0.004% ) 974011 branches # 362.605 M/sec ( +- 0.005% ) 35187 branch-misses # 3.613 % ( +- 0.027% ) cache-references cache-misses 0.022597372 seconds time elapsed ( +- 0.981% ) real 0m23.054s user 0m0.380s sys 0m0.000s Patched: marge:~ # time perf stat --repeat=1000 cgexec -g cpu:test sh -c exit Performance counter stats for 'cgexec -g cpu:test sh -c exit' (1000 runs): 2.639303 task-clock-msecs # 0.915 CPUs ( +- 0.051% ) 1 context-switches # 0.000 M/sec ( +- 1.048% ) 0 CPU-migrations # 0.000 M/sec ( +- 21.602% ) 633 page-faults # 0.240 M/sec ( +- 0.003% ) 3883572 cycles # 1471.439 M/sec ( +- 1.767% ) 4830809 instructions # 1.244 IPC ( +- 0.191% ) 975204 branches # 369.493 M/sec ( +- 0.009% ) 35314 branch-misses # 3.621 % ( +- 0.060% ) cache-references cache-misses 0.002884424 seconds time elapsed ( +- 0.055% ) real 0m3.329s user 0m0.012s sys 0m0.352s -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/