From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759850Ab2C2RoA (ORCPT ); Thu, 29 Mar 2012 13:44:00 -0400 Received: from va3ehsobe001.messaging.microsoft.com ([216.32.180.11]:14820 "EHLO va3outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752662Ab2C2Rn5 (ORCPT ); Thu, 29 Mar 2012 13:43:57 -0400 X-SpamScore: -17 X-BigFish: VPS-17(zzbb2dI9371I1454I1432N98dK1447Mzz1202hzzz2fh668h839h93fhd25h) X-Forefront-Antispam-Report: CIP:160.33.98.74;KIP:(null);UIP:(null);IPV:NLI;H:mail7.fw-bc.sony.com;RD:mail7.fw-bc.sony.com;EFVD:NLI Message-ID: <4F749F47.4040500@am.sony.com> Date: Thu, 29 Mar 2012 10:43:35 -0700 From: Tim Bird User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7 MIME-Version: 1.0 To: Daniel Walker CC: "linux-kernel@vger.kernel.org" , "kernel-team@android.com" Subject: Re: [RFC] Android Logger vs. Shared Memory FIGHT! References: <20120328210631.GB2297@fifo99.com> <20120329145055.GE13912@fifo99.com> <4F748CF6.4010205@am.sony.com> <20120329170930.GD16476@fifo99.com> In-Reply-To: <20120329170930.GD16476@fifo99.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-OriginatorOrg: am.sony.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/29/2012 10:09 AM, Daniel Walker wrote: > John Stultz commented on how gettimeofday() is more accurate that what > is needed. Logger actually uses a less accurate, and faster, method of timing. > The time isn't exactly apples to apples, my shared memory example is actually > using a slower clock compared to logger. OK - that's interesting. > >> >> Tests were 60 seconds. I presume there were multiple runs and these are >> averages. Can you provide the number of runs and the standard deviation for >> each set? > > > Test cases were 600 seconds (10 minutes) .. There were three runs. > Here's the raw data, all in bytes per second: > > X86: > Logger TSC = 70072480.0, 83911562.7, 78610971.8 > Shared Memory TSC = 460262336.0, 454204684.1, 457050682.2 > > Logger ACPI_PM = 75523320.0, 81615111.9, 81588600.2 > Shared Memory ACPI_PM = 29688532.0, 28211029.2, 28225661.6 > > > ARM: > Logger = 6985508.0, 5827587.3, 7034293.7 > Shared Memory = 12371886.7, 18362639.9, 15274489.3 > You can feel free to compute the standard deviation if you wish. Here are the std deviations: x86-logger-tsc: 7.4% x86-shmem-tsc: 0.5% x86-logger-ACPI_PM: 3.6% x86-shmem-ACPI_PM: 2.4% ARM-logger: 8.4% ARM-shmem: 15.9% Performance ratios: x86-shmem-tsc/x86-logger-tsc -> 5.9 x86-shmem-ACPI_PM/x86-logger-ACPI_PM -> 0.36 ARM-shem/ARM-logger -> 2.3 It would be nice to understand why the ARM numbers are not more consistent. I'll try to take a look at this next week. Thanks for the data. I recently started work on my own performance test suite for logger. I'm taking the approach of simulating log insertions based on log timings from a sampled device, and measuring cost per message. I'm not sure when I'll finish it, but I'll post results when I have them. -- Tim ============================= Tim Bird Architecture Group Chair, CE Workgroup of the Linux Foundation Senior Staff Engineer, Sony Network Entertainment =============================