From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 23 Jan 2003 09:49:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 23 Jan 2003 09:49:34 -0500 Received: from robur.slu.se ([130.238.98.12]:57362 "EHLO robur.slu.se") by vger.kernel.org with ESMTP id ; Thu, 23 Jan 2003 09:49:33 -0500 From: Robert Olsson MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15920.796.897388.111085@robur.slu.se> Date: Thu, 23 Jan 2003 15:58:36 +0100 To: Ben Greear Cc: linux-kernel , Robert.Olsson@data.slu.se Subject: ksoftirqd_CPU0 spinning in 2.4.21-pre3 In-Reply-To: <3E2EF490.20402@candelatech.com> References: <3E2EF490.20402@candelatech.com> X-Mailer: VM 6.92 under Emacs 19.34.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ben Greear writes: > I happened to notice that my ksoftirqd_CPU0 process started spinning > at 99% CPU when I plugged in the ports to a tulip NIC. I didn't see > any significant amount of interrupts when I looked at /proc/interrupts, > and there was no traffic running. > > However, this is also running a hacked up tulip-napi driver, so it > could very well be my problem. I have not seen this on any other kernel > in several months though... > > Anyway, if anyone has seen this, I'd like to know. Otherwise, I'll blame > my code and start poking at things... Well it can be normal operation if box is highly loaded... At high loads network interrupts are disabled not to trash performance or DoS the kernel. Which in turn does succesive polls via RX-softirq to devices at rate the it can process. So no interrupts when resources are scarce. The lack of interrupts makes ksoftirqd run the RX-softirq so the network load becomes visable here. Also review the discussion about ksoftirqd priority. Cheers. --ro