From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [ofa-general] Re: [PATCH 2/3][NET_BATCH] net core use batching Date: Tue, 09 Oct 2007 13:43:31 -0700 (PDT) Message-ID: <20071009.134331.35664207.davem@davemloft.net> References: <470AD5D7.1070000@garzik.org> <20071008.184126.124062865.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: johnpol@2ka.mipt.ru, Robert.Olsson@data.slu.se, herbert@gondor.apana.org.au, gaagaan@gmail.com, shemminger@linux-foundation.org, netdev@vger.kernel.org, rdreier@cisco.com, peter.p.waskiewicz.jr@intel.com, hadi@cyberus.ca, mcarlson@broadcom.com, jeff@garzik.org, general@lists.openfabrics.org, mchan@broadcom.com, tgraf@suug.ch, randy.dunlap@oracle.com, jagana@us.ibm.com, kaber@trash.net, sri@us.ibm.com To: andi@firstfloor.org Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: general-bounces@lists.openfabrics.org Errors-To: general-bounces@lists.openfabrics.org List-Id: netdev.vger.kernel.org From: Andi Kleen Date: 09 Oct 2007 18:51:51 +0200 > Hopefully that new qdisc will just use the TX rings of the hardware > directly. They are typically large enough these days. That might avoid > some locking in this critical path. Indeed, I also realized last night that for the default qdiscs we do a lot of stupid useless work. If the queue is a FIFO and the device can take packets, we should send it directly and not stick it into the qdisc at all. > If the data is just passed on to the hardware queue, why is any > locking needed at all? (except for the driver locking of course) Absolutely. Our packet scheduler subsystem is great, but by default it should just get out of the way.