From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: task switch from net-rx to idle when there is napi processing to be done Date: Wed, 25 Jan 2012 09:55:23 +0100 Message-ID: <20120125085523.GG6305@pengutronix.de> References: <4F1F6B66.5010005@caviumnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: RT To: Venkat Subbiah Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:35768 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753999Ab2AYIzZ (ORCPT ); Wed, 25 Jan 2012 03:55:25 -0500 Content-Disposition: inline In-Reply-To: <4F1F6B66.5010005@caviumnetworks.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hello, On Tue, Jan 24, 2012 at 06:39:34PM -0800, Venkat Subbiah wrote: > In the process of debugging a napi ethernet driver performance > issue, what I am noticing is >=20 > 1. While the driver is in the middle of a napi packet processing > loop, there is a task switch from > sirq-net-rx to idle even though there is pending napi processing to b= e done. I didn't check your logs below, but maybe this is related to the defaul= t settings in /proc/sys/kernel/sched_rt_period_us and /proc/sys/kernel/sched_rt_runtime_us? That is 0.05s per second is reserved for non-RT tasks tasks such that a run-away realtime process will not lock up the machine. To verify that, try echo -1 > /proc/sys/kernel/sched_rt_runtime_us =2E Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= | -- 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