From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] PATCH 1/2 [SCHED 2.6.24]: Check subqueue status before calling hard_start_xmit Date: Tue, 13 Nov 2007 20:41:14 -0800 (PST) Message-ID: <20071113.204114.28838694.davem@davemloft.net> References: <20071113174444.27916.1892.stgit@localhost.localdomain> <20071113174450.27916.80538.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: peter.p.waskiewicz.jr@intel.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:55140 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1758835AbXKNElP (ORCPT ); Tue, 13 Nov 2007 23:41:15 -0500 In-Reply-To: <20071113174450.27916.80538.stgit@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: PJ Waskiewicz Date: Tue, 13 Nov 2007 09:44:50 -0800 > The only qdiscs that check subqueue state before dequeue'ing are PRIO > and RR. The other qdiscs, including the default pfifo_fast qdisc, will > allow traffic bound for subqueue 0 through to hard_start_xmit. The check > for netif_queue_stopped() is done above in pkt_sched.h, so it is > unnecessary for qdisc_restart(). However, if the underlying driver is > multiqueue capable, and only sets queue states on subqueues, this will > allow packets to enter the driver when it's currently unable to process > packets, resulting in expensive requeues and driver entries. This patch > re-adds the check for the subqueue status before calling hard_start_xmit, > so we can try and avoid the driver entry when the queues are stopped. > > Signed-off-by: Peter P Waskiewicz Jr Applied, and I'll queue up the other one for -stable, thanks.