From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: 3.14-rt ARM performance regression? Date: Tue, 27 Jan 2015 23:08:46 -0500 Message-ID: <20150127230846.12aaf405@gandalf.local.home> References: <20150124020341.GA2861@jcartwri.amer.corp.natinst.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-rt-users@vger.kernel.org, Thomas Gleixner , Sebastian Andrzej Siewior To: Josh Cartwright Return-path: Received: from smtprelay0022.hostedemail.com ([216.40.44.22]:46176 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759991AbbA1EIt (ORCPT ); Tue, 27 Jan 2015 23:08:49 -0500 In-Reply-To: <20150124020341.GA2861@jcartwri.amer.corp.natinst.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Fri, 23 Jan 2015 20:03:41 -0600 Josh Cartwright wrote: > Hey folks- > > We've recently undertaken an upgrade of our kernel from 3.2-rt to > 3.14-rt, and have run into a performance regression on our ARM boards. > We're still in the process of trying to isolate what we can, but > hopefully someone's already run into this and has a solution or might > have some useful debugging ideas. > > The first test we did was to run cyclictest[1] for comparison: > > 3.2.35-rt52 > # Total: 312028761 312028761 624057522 > # Min Latencies: 00010 00011 > # Avg Latencies: 00018 00020 > # Max Latencies: 00062 00066 00066 > # Histogram Overflows: 00000 00000 00000 > > 3.14.25-rt22 > # Total: 304735655 304735657 609471312 > # Min Latencies: 00013 00013 > # Avg Latencies: 00023 00024 > # Max Latencies: 00086 00083 00086 > # Histogram Overflows: 00000 00000 00000 > I'm curious if the vanilla kernels (non-rt) show the same regression. Max latencies for vanilla kernels will probably go through the roof, but the min and average should give you some hint. -- Steve