From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: FSCKED clock sources WAS(Re: [WIP][PATCHES] Network xmit batching Date: Thu, 21 Jun 2007 11:54:17 -0400 Message-ID: <1182441257.5017.48.camel@localhost> References: <20070619140038.GA13629@2ka.mipt.ru> <1182270529.4968.73.camel@localhost> <18040.5105.715624.286924@robur.slu.se> <20070619.152801.99185860.davem@davemloft.net> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="=-wZ+pykPA+5ASPePiUDXs" Cc: Robert.Olsson@data.slu.se, johnpol@2ka.mipt.ru, krkumar2@in.ibm.com, gaagaan@gmail.com, netdev@vger.kernel.org, rick.jones2@hp.com, sri@us.ibm.com To: David Miller Return-path: Received: from wx-out-0506.google.com ([66.249.82.237]:36023 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757119AbXFUPyW (ORCPT ); Thu, 21 Jun 2007 11:54:22 -0400 Received: by wx-out-0506.google.com with SMTP id t15so552830wxc for ; Thu, 21 Jun 2007 08:54:21 -0700 (PDT) In-Reply-To: <20070619.152801.99185860.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org --=-wZ+pykPA+5ASPePiUDXs Content-Type: text/plain Content-Transfer-Encoding: 7bit On Tue, 2007-19-06 at 15:28 -0700, David Miller wrote: > Converting pktgen over to ktime_t might be a nice cleanup. Would that really solve it? i.e doesnt it still tie to what the clock source is? I had a friend of mine (Robert, you know Jeremy) and results are slightly different from what Evginy found. The summary is: Batching always is better, jiffies is always the better clock source (and who would have thunk,eh? Opteron kicks a Xeons ass). Attached results. Evgeniy, did you sync on the batching case with the git tree? Can you describe your hardware in /proc/cpuinfo and /proc/interupts? cheers, jamal --=-wZ+pykPA+5ASPePiUDXs Content-Disposition: attachment; filename=batch-clock-res Content-Type: text/plain; name=batch-clock-res; charset=us-ascii Content-Transfer-Encoding: 7bit The test variables are: ---------------------- 1) A Intel Xeon[1] machine vs an AMD opteron[2]. 2) A plain 2622-rc4 kernel vs a 2622-rc4 with batching (from git://git.kernel.org/pub/scm/linux/kernel/git/hadi/batch-lin26.git) 3) Different clock sources acpi-pm, jiffies and tsc Test setup ----------- pktgen was used to send from the system under test (where test variables #2-#3 were adjusted) to a second box. CPU affinity was tied to cpu2 in all case to reduce variables in all test cases... Test validation --------------- Throughput results were confirmed to match on receiver and sender (as reported by pktgen) Results ------- The AMD opteron always had better results. The batching kernels always was better than non-batching. The jiffies clock was always the most consistent and gave best performance Kernel-type | acpi-pm clock | jiffies clock | tsc clock | +h/ware | | | | ------------+---------------+---------------+-----------+ 2622-rc4 | 347Kpps | 1.40 Mpps | 1.36Mpps | plain | | | | Intel Xeon | | | | ------------+---------------+---------------+-----------+ 2622-rc4 | 342Kpps | 853 kpps | 821kpps | plain | | | | AMD opteron | | | | ------------+---------------+---------------+-----------+ 2622-rc4 | 615Kpps | 1.46 Mpps | 1.46Mpps | batch | | | | Intel Xeon | | | | ------------+---------------+---------------+-----------+ 2622-rc4 | 633Kpps | 1.18 Mpps | 1.17Mpps | batch | | | | AMD opteron | | | | ------------+---------------+---------------+-----------+ The two systems under test --------------------------- [1]------------- vendor_id : GenuineIntel cpu family : 15 model : 4 model name : Intel(R) Xeon(TM) CPU 2.80GHz stepping : 1 cpu MHz : 2793.329 cache size : 1024 KB physical id : 3 siblings : 2 core id : 0 cpu cores : 1 ------------- [2]------------- vendor_id : AuthenticAMD cpu family : 15 model : 33 model name : Dual Core AMD Opteron(tm) Processor 275 stepping : 2 cpu MHz : 2194.778 cache size : 1024 KB physical id : 1 siblings : 2 core id : 1 cpu cores : 2 --------------------------------------------- --=-wZ+pykPA+5ASPePiUDXs--