From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: [ofa-general] Re: [PATCH 03/10] dev.c changes. Date: Fri, 20 Jul 2007 13:55:37 +0200 Message-ID: <46A0A2B9.1050504@trash.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: jagana@us.ibm.com, johnpol@2ka.mipt.ru, herbert@gondor.apana.org.au, gaagaan@gmail.com, Robert.Olsson@data.slu.se, kumarkr@linux.ibm.com, 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, netdev@vger.kernel.org, davem@davemloft.net, sri@us.ibm.com To: Krishna Kumar2 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 Krishna Kumar2 wrote: > Patrick McHardy wrote on 07/20/2007 04:50:37 PM >> Is there any downside in using batching with smaller queue sizes? >> > > I think there is, but as yet I don't have any data (and 16 is probably > higher > than reqd) to show it. If the queue size is very small (like 4), the extra > processing to maintain this list may take more cycles than the performance > gains for sending out few skbs, esp since most xmits will send out 1 skb > and > skb batching takes places less often (when tx lock fails or queue gets > full). > > OTOH, there might be a gain to even send out 2 skbs, the problem is in > doing > the extra processing before xmit and not at the time of xmit. > > Does this sound OK ? If so, I will add the code to implement the TODO for > tx_queue_len checking too. > I can't really argue about the numbers, but it seems to me that only devices which *usually* have a sufficient queue length will support this, and anyone setting the queue length of a gbit device to <16 is begging for trouble anyway. So it doesn't really seem worth to bloat the code for handling an insane configuration as long as it doesn't break.