From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gilles Chanteperdrix Subject: Re: Improving ARM7 platform performance with CONFIG_PREEMPT_RT Date: Wed, 12 Sep 2012 22:29:00 +0200 Message-ID: <5050F08C.1070801@xenomai.org> References: <02D8B38C-C6C2-43A8-B601-721B48612106@thebigcorporation.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Hartmut Behrens , linux-rt-users@vger.kernel.org To: Sven-Thorsten Dietrich Return-path: Received: from xenomai.org ([88.191.95.136]:38712 "EHLO xenomai.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752467Ab2ILU3E (ORCPT ); Wed, 12 Sep 2012 16:29:04 -0400 In-Reply-To: <02D8B38C-C6C2-43A8-B601-721B48612106@thebigcorporation.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 09/12/2012 09:01 PM, Sven-Thorsten Dietrich wrote: > > On Sep 12, 2012, at 3:20 AM, Hartmut Behrens > wrote: > >> Hi, >> >> I have patched a 3.2 kernel for a OMAP compatible processor (ARM >> Cortex A8) to be used on an Gumstix Overo with the >> CONFIG_PREEMPT_RT patch. >> >> I have noticed that the latency of the patched kernel on this >> platform is <300usec (using cyclictest), similar to what is >> reported for the ARM9 platforms at >> https://rt.wiki.kernel.org/index.php/CONFIG_PREEMPT_RT_Patch >> >> Is this the best performance that can be expected from ARM7/9 >> platforms? >> >> Could it be improved by using different kernel config settings - >> e.g. CONFIG_LATENCY_TRACE=n - >> https://rt.wiki.kernel.org/index.php/Cyclictest mentions that >> latency tracing adds significant kernel overhead? > > > There are a lot of options that can be eliminated / optimized to > reduce memory footprint and overhead. One of these options is, maybe surprisingly, CONFIG_THUMB2_KERNEL. -- Gilles.