Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 3 Oct 2001 05:24:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 3 Oct 2001 05:24:29 -0400 Received: from chiara.elte.hu ([157.181.150.200]:47879 "HELO chiara.elte.hu") by vger.kernel.org with SMTP id ; Wed, 3 Oct 2001 05:24:15 -0400 Date: Wed, 3 Oct 2001 11:22:18 +0200 (CEST) From: Ingo Molnar Reply-To: To: Ben Greear Cc: Benjamin LaHaise , jamal , , Alexey Kuznetsov , Robert Olsson , Subject: Re: [announce] [patch] limiting IRQ load, irq-rewrite-2.4.11-B5 In-Reply-To: <3BB956D3.AE0FCC54@candelatech.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 1 Oct 2001, Ben Greear wrote: > So, when you turn off the IRQs, are the drivers somehow made aware of > this so that they can go into polling mode? That might fix the 10ms > latency/starvation problem that bothers me... the latest, -D9 patch does this. If drivers provide a (backwards compatible) ->poll_controller() call then they can be polled by kpolld. There are also a few points within the networking code that trigger a poll pass, to make sure events are processed even if networking-intensive applications take away all CPU time from kpolld. The device is only polled if the IRQ is detected to be in overload mode. IRQ-overload protection does not depend on the existence of the availability of the ->poll_controller(). The poll_controller() call is very simple for most drivers. (It has to be per-driver, because not all drivers advance their state purely via their device interrupts.) but kpolld itself and auto-mitigation is not limited to networking - any other driver framework that has high-irq-load problems can use it. > I'm more worried about dropped pkts. If you can receive 10k packets > per second, then you can receive (lose) 100 packets in 10ms.... yep - this does not happen anymore, at least under the loads i tested which otherwise choke a purely irq-driven machine. (It will happen in a gradual way if load is increased further, but that is natural.) Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/