Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968060AbXEHMQd (ORCPT ); Tue, 8 May 2007 08:16:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S967504AbXEHMQc (ORCPT ); Tue, 8 May 2007 08:16:32 -0400 Received: from rhun.apana.org.au ([64.62.148.172]:3333 "EHLO arnor.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S968013AbXEHMQa (ORCPT ); Tue, 8 May 2007 08:16:30 -0400 Date: Tue, 8 May 2007 22:16:09 +1000 From: Herbert Xu To: "David S. Miller" , Jeremy Fitzhardinge Cc: Christoph Hellwig , Andi Kleen , Andrew Morton , virtualization@lists.osdl.org, lkml , Chris Wright , Ian Pratt , Christian Limpach , netdev@vger.kernel.org, Jeff Garzik , Stephen Hemminger , Rusty Russell , Keir Fraser Subject: [2/2] [NET] link_watch: Remove delay for up even when we're down Message-ID: <20070508121609.GA24763@gondor.apana.org.au> References: <20070504232051.411946839@goop.org> <20070504232121.492190579@goop.org> <20070505091624.GA8890@infradead.org> <463C56D3.8060609@goop.org> <20070505102305.GA12771@gondor.apana.org.au> <463F95C3.60407@goop.org> <20070508121322.GA21647@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070508121322.GA21647@gondor.apana.org.au> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4450 Lines: 160 [NET]: Remove link_watch delay for up even when we're down Currently all link carrier events are delayed by up to a second before they're processed to prevent link storms. This causes unnecessary packet loss during that interval. In fact, we can achieve the same effect in preventing storms by only delaying down events and unnecssary up events. The latter is defined as up events when we're already up. Signed-off-by: Herbert Xu Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- diff --git a/net/core/link_watch.c b/net/core/link_watch.c index 71a35da..b5f4579 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -77,11 +77,52 @@ static void rfc2863_policy(struct net_device *dev) } -/* Must be called with the rtnl semaphore held */ -void linkwatch_run_queue(void) +static int linkwatch_urgent_event(struct net_device *dev) +{ + return netif_running(dev) && netif_carrier_ok(dev) && + dev->qdisc != dev->qdisc_sleeping; +} + + +static void linkwatch_add_event(struct net_device *dev) +{ + unsigned long flags; + + spin_lock_irqsave(&lweventlist_lock, flags); + dev->link_watch_next = lweventlist; + lweventlist = dev; + spin_unlock_irqrestore(&lweventlist_lock, flags); +} + + +static void linkwatch_schedule_work(unsigned long delay) +{ + if (test_and_set_bit(LW_RUNNING, &linkwatch_flags)) + return; + + /* If we wrap around we'll delay it by at most HZ. */ + if (delay > HZ) + delay = 0; + + schedule_delayed_work(&linkwatch_work, delay); +} + + +static void __linkwatch_run_queue(int urgent_only) { struct net_device *next; + /* + * Limit the number of linkwatch events to one + * per second so that a runaway driver does not + * cause a storm of messages on the netlink + * socket. This limit does not apply to up events + * while the device qdisc is down. + */ + if (!urgent_only) + linkwatch_nextevent = jiffies + HZ; + clear_bit(LW_RUNNING, &linkwatch_flags); + spin_lock_irq(&lweventlist_lock); next = lweventlist; lweventlist = NULL; @@ -92,6 +133,11 @@ void linkwatch_run_queue(void) next = dev->link_watch_next; + if (urgent_only && !linkwatch_urgent_event(dev)) { + linkwatch_add_event(dev); + continue; + } + /* * Make sure the above read is complete since it can be * rewritten as soon as we clear the bit below. @@ -116,21 +162,23 @@ void linkwatch_run_queue(void) dev_put(dev); } + + if (lweventlist) + linkwatch_schedule_work(linkwatch_nextevent - jiffies); } -static void linkwatch_event(struct work_struct *dummy) +/* Must be called with the rtnl semaphore held */ +void linkwatch_run_queue(void) { - /* Limit the number of linkwatch events to one - * per second so that a runaway driver does not - * cause a storm of messages on the netlink - * socket - */ - linkwatch_nextevent = jiffies + HZ; - clear_bit(LW_RUNNING, &linkwatch_flags); + __linkwatch_run_queue(0); +} + +static void linkwatch_event(struct work_struct *dummy) +{ rtnl_lock(); - linkwatch_run_queue(); + __linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies)); rtnl_unlock(); } @@ -138,23 +186,19 @@ static void linkwatch_event(struct work_struct *dummy) void linkwatch_fire_event(struct net_device *dev) { if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) { - unsigned long flags; + unsigned long delay; dev_hold(dev); - spin_lock_irqsave(&lweventlist_lock, flags); - dev->link_watch_next = lweventlist; - lweventlist = dev; - spin_unlock_irqrestore(&lweventlist_lock, flags); + linkwatch_add_event(dev); - if (!test_and_set_bit(LW_RUNNING, &linkwatch_flags)) { - unsigned long delay = linkwatch_nextevent - jiffies; + delay = linkwatch_nextevent - jiffies; - /* If we wrap around we'll delay it by at most HZ. */ - if (delay > HZ) - delay = 0; - schedule_delayed_work(&linkwatch_work, delay); - } + /* Minimise down-time: drop delay for up event. */ + if (linkwatch_urgent_event(dev)) + delay = 0; + + linkwatch_schedule_work(delay); } } - 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/