From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clark Williams Subject: Re: 1us latency? Date: Mon, 3 Aug 2015 11:44:22 -0500 Message-ID: <20150803114422.0efbea1b@sluggy> References: <55BF4CD7.8000007@pavlinux.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Linux RT Users To: pavel Return-path: Received: from mx1.redhat.com ([209.132.183.28]:52195 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753524AbbHCQoZ (ORCPT ); Mon, 3 Aug 2015 12:44:25 -0400 In-Reply-To: <55BF4CD7.8000007@pavlinux.ru> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Mon, 3 Aug 2015 14:13:27 +0300 pavel wrote: > # ./cyclictest -S -p fifo > defaulting realtime priority to 9 > # /dev/cpu_dma_latency set to 0us > policy: fifo: loadavg: 0.00 0.03 0.05 1/218 4240 > > T: 0 ( 4174) P: 9 I:1000 C: 430806 Min: 1 Act: 1 Avg: 1 Max: 10 > T: 1 ( 4175) P: 9 I:1500 C: 287204 Min: 1 Act: 1 Avg: 1 Max: 6 > T: 2 ( 4176) P: 9 I:2000 C: 215403 Min: 1 Act: 2 Avg: 1 Max: 11 > T: 3 ( 4177) P: 9 I:2500 C: 172322 Min: 1 Act: 1 Avg: 1 Max: 9 > T: 4 ( 4178) P: 9 I:3000 C: 143602 Min: 1 Act: 1 Avg: 1 Max: 10 > T: 5 ( 4179) P: 9 I:3500 C: 123087 Min: 1 Act: 1 Avg: 1 Max: 11 > T: 6 ( 4180) P: 9 I:4000 C: 107701 Min: 1 Act: 1 Avg: 1 Max: 10 > T: 7 ( 4181) P: 9 I:4500 C: 108232 Min: 1 Act: 2 Avg: 1 Max: 11 > > > It possible? 1us latency? o_O > > kernel- 3.18.19-rt15 > cyclictest V 0.92 > Intel(R) Xeon(R) CPU E3-1246 v3 @ 3.50GHz > MSI MS-7823/B85M-G43 (MS-7823), BIOS V3.14B3 06/23/2014 > -- No, your latency is 11us. Max latency is what we care about, not the average.