From mboxrd@z Thu Jan 1 00:00:00 1970 From: Iratxo Pichel Ortiz Subject: Re: NOHZ: local_softirq_pending Date: Thu, 18 Jun 2009 18:52:09 +0200 Message-ID: <4A3A70B9.4070702@albentia.com> References: <4A35171C.9090800@albentia.com> <8e6b7a710906141250m2a991ca9r5949e502b9976e39@mail.gmail.com> <4A365CCF.2020707@albentia.com> <8e6b7a710906160101x6a8ae9d5qa7638627f513278@mail.gmail.com> <4A376450.5020209@albentia.com> <4A376559.5060604@albentia.com> <4A37B014.4040104@albentia.com> <4A37E6D1.5010207@albentia.com> <4A396FB8.3020807@albentia.com> <4A398B4F.6080702@albentia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-rt-users , =?ISO-8859-1?Q?Noeli?= =?ISO-8859-1?Q?a_Mor=F3n?= , 'Rodrigo Partearroyo' To: Thomas Gleixner Return-path: Received: from llsc497-a04.servidoresdns.net ([82.223.190.48]:43579 "EHLO llsc497-a04.servidoresdns.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750794AbZFRQwR (ORCPT ); Thu, 18 Jun 2009 12:52:17 -0400 In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: Thomas, Thomas Gleixner wrote: > No, what happens is that the -RT starvation protector kicks in. That'= s > a mechanism which checks whether the CPU is monopolized by rt tasks > for longer than 950ms. It then blocks execution of rt tasks for > 50ms. The silly thing is that it goes idle, but that's a different > problem. > =20 > It's default on and can be disabled via: > > echo 0 > /proc/sys/kernel/rt_runtime_us > > Sorry that I did not notice that earlier, but when that triggers, the= n > something is really wrong. There should never be a situation where -r= t > tasks (neither irq threads nor softirqs) should monopolize the CPU. > =20 No problem at all! Please let me know if the following assumption is=20 right: This protection mechanism is dependent on the available CPU=20 power. I mean, if the system has low CPU power, and if, for example, th= e=20 network has very very high load, the total time taken to process all th= e=20 data will be long. Generally much longer than in more powerful systems,= =20 so this protection arises. Is this right or it should not happen by=20 design of the softirqs/RT tasks? Anyway, seems to be correctly working. I still have to check why with =20 HZ=3D100 it was periodically happening this events even with low load, = but=20 that could be very probably related to my software. Again, thank you very much. Best regards, Iratxo. > Thanks, > > tglx > > =20 --=20 Iratxo Pichel Ortiz Software Development Manager Albentia Systems S.A. http://www.albentia.com Tel: +34 914400567 Cel: +34 663808405 =46ax: +34 914400569 C\Margarita Salas 22 Parque Tecnol=F3gico de Legan=E9s Legan=E9s (28918) Madrid Spain -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html