Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753561Ab0FORwD (ORCPT ); Tue, 15 Jun 2010 13:52:03 -0400 Received: from hera.kernel.org ([140.211.167.34]:49934 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752535Ab0FORwA (ORCPT ); Tue, 15 Jun 2010 13:52:00 -0400 Message-ID: <4C17BD94.6080601@kernel.org> Date: Tue, 15 Jun 2010 19:51:16 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 MIME-Version: 1.0 To: Jonathan Corbet CC: mingo@elte.hu, tglx@linutronix.de, bphilips@suse.de, yinghai@kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, jeff@garzik.org Subject: Re: [PATCH 06/12] irq: implement irq_schedule_poll() References: <1276443098-20653-1-git-send-email-tj@kernel.org> <1276443098-20653-7-git-send-email-tj@kernel.org> <20100615114058.32e58afd@bike.lwn.net> In-Reply-To: <20100615114058.32e58afd@bike.lwn.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Tue, 15 Jun 2010 17:51:18 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 41 On 06/15/2010 07:40 PM, Jonathan Corbet wrote: > On Sun, 13 Jun 2010 17:31:32 +0200 > Tejun Heo wrote: > >> Implement and use irq_schedule_poll() to schedule desc->poll_timer >> instead of calling mod_timer directly. irq_schedule_poll() is called >> with desc->lock held and schedules the timer iff necessary - ie. if >> the timer is offline or scheduled to expire later than requested. >> This will be used to share desc->poll_timer. > > One quick question... > >> diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c >> index 0bce0e3..0b8fd0a 100644 >> --- a/kernel/irq/spurious.c >> +++ b/kernel/irq/spurious.c >> @@ -23,6 +23,8 @@ enum { >> >> /* IRQ polling common parameters */ >> IRQ_POLL_INTV = HZ / 100, /* from the good ol' 100HZ tick */ >> + >> + IRQ_POLL_SLACK = HZ / 1000, /* 10% slack */ >> }; > > Why would IRQ_POLL_SLACK be anything other than zero for HZ < 1000? > It seems like you'd get no slack at all on most systems. Am I missing > something? Jiri questioned the same thing. I'll bump it to HZ / 250 so that it at least has one tick slack on 250HZ configuration which is pretty common these days. Thanks. -- tejun -- 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/