Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752079AbbECNYA (ORCPT ); Sun, 3 May 2015 09:24:00 -0400 Received: from mail-wg0-f45.google.com ([74.125.82.45]:34747 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750927AbbECNXx (ORCPT ); Sun, 3 May 2015 09:23:53 -0400 Message-ID: <1430659432.4233.3.camel@gmail.com> Subject: Re: [PATCH 3/3] context_tracking,x86: remove extraneous irq disable & enable from context tracking on syscall entry From: Mike Galbraith To: Rik van Riel Cc: Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, williams@redhat.com, luto@kernel.org, fweisbec@redhat.com, peterz@infradead.org, heiko.carstens@de.ibm.com, tglx@linutronix.de, Ingo Molnar , Paolo Bonzini Date: Sun, 03 May 2015 15:23:52 +0200 In-Reply-To: <554399D1.6010405@redhat.com> References: <1430429035-25563-1-git-send-email-riel@redhat.com> <1430429035-25563-4-git-send-email-riel@redhat.com> <20150501064044.GA18957@gmail.com> <554399D1.6010405@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 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 Content-Length: 2763 Lines: 70 On Fri, 2015-05-01 at 11:20 -0400, Rik van Riel wrote: > On 05/01/2015 02:40 AM, Ingo Molnar wrote: > > >> This patch builds on top of these patches by Paolo: > >> https://lkml.org/lkml/2015/4/28/188 > >> https://lkml.org/lkml/2015/4/29/139 > >> > >> Together with this patch I posted earlier this week, the syscall path > >> on a nohz_full cpu seems to be about 10% faster. > >> https://lkml.org/lkml/2015/4/24/394 > >> > >> My test is a simple microbenchmark that calls getpriority() in a loop > >> 10 million times: > >> > >> run time system time > >> vanilla 5.49s 2.08s > >> __acct patch 5.21s 1.92s > >> both patches 4.88s 1.71s > > > > Just curious, what are the numbers if you don't have context tracking > > enabled, i.e. without nohz_full? > > > > I.e. what's the baseline we are talking about? > > It's an astounding difference. This is not a kernel without nohz_full, > just a CPU without nohz_full running the same kernel I tested with > yesterday: > > run time system time > vanilla 5.49s 2.08s > __acct patch 5.21s 1.92s > both patches 4.88s 1.71s > CPU w/o nohz 3.12s 1.63s <-- your numbers, mostly Below are v4.1-rc1-172-g6c3c1eb3c35e + patches measurements. 100M * stat() on isolated cpu NO_HZ_FULL off inactive housekeeper nohz_full real 0m14.266s 0m14.367s 0m20.427s 0m27.921s user 0m1.756s 0m1.553s 0m1.976s 0m10.447s sys 0m12.508s 0m12.769s 0m18.400s 0m17.464s (real) 1.000 1.007 1.431 1.957 1.000 1.000 real 0m20.423s 0m27.930s +rik 1,2 user 0m2.072s 0m10.450s sys 0m18.304s 0m17.471s vs off 1.431 1.957 vs prev 1.000 1.000 real 0m20.256s 0m27.803s +paolo 1,2 (2 missing prototypes) user 0m1.884s 0m10.551s sys 0m18.353s 0m17.242s vs off 1.419 1.948 vs prev .991 .995 real 0m19.122s 0m26.946s +rik 3 user 0m1.896s 0m10.292s sys 0m17.198s 0m16.644s vs off 1.340 1.888 vs prev .944 .969 -- 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/