From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030305AbVLGBbB (ORCPT ); Tue, 6 Dec 2005 20:31:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965046AbVLGBbB (ORCPT ); Tue, 6 Dec 2005 20:31:01 -0500 Received: from viper.oldcity.dca.net ([216.158.38.4]:58292 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S964852AbVLGBbA (ORCPT ); Tue, 6 Dec 2005 20:31:00 -0500 Subject: Re: Softirq preemption From: Lee Revell To: Ingo Molnar Cc: linux-kernel In-Reply-To: <1133464131.7898.30.camel@mindpipe> References: <1133464131.7898.30.camel@mindpipe> Content-Type: multipart/mixed; boundary="=-i9sgIHp5a1N9/Y8m/FHc" Date: Tue, 06 Dec 2005 20:31:48 -0500 Message-Id: <1133919109.15592.22.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.4.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-i9sgIHp5a1N9/Y8m/FHc Content-Type: text/plain Content-Transfer-Encoding: 7bit On Thu, 2005-12-01 at 14:08 -0500, Lee Revell wrote: > Ingo, > > Is there any chance that the softirq preemption feature from the -rt > kernel can be pushed upstream? > FWIW, here is the longest latency I see with 2.6.14-rt22, with the same preemption settings as 2.6.14 + PREEMPT. AFAICT a longish network softirq gets interrupted by several disk and network interrupts which adds up to ~1ms. Is there any easy way to break up this code path that could be acceptable for mainline, or does this seem like a reasonable lower limit on achievable latency (until/unless PREEMPT_RT gets merged etc)? 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