From mboxrd@z Thu Jan 1 00:00:00 1970 From: Karl Hiramoto Subject: Re: [Linux-ATM-General] [PATCH] atm/br2684: netif_stop_queue() when atm device busy and netif_wake_queue() when we can send packets again. Date: Tue, 15 Sep 2009 15:44:53 +0200 Message-ID: <4AAF9A55.8030207@hiramoto.org> References: <1251545092-18081-1-git-send-email-karl@hiramoto.org> <4AA95838.4010007@redfish-solutions.com> <4AA97004.2010904@hiramoto.org> <20090911.114848.177667600.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: philipp_subx@redfish-solutions.com, netdev@vger.kernel.org, linux-atm-general@lists.sourceforge.net To: David Miller Return-path: Received: from caiajhbdcaid.dreamhost.com ([208.97.132.83]:54831 "EHLO spunkymail-a11.g.dreamhost.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754116AbZIONow (ORCPT ); Tue, 15 Sep 2009 09:44:52 -0400 In-Reply-To: <20090911.114848.177667600.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: David Miller wrote: > From: Karl Hiramoto > Date: Thu, 10 Sep 2009 23:30:44 +0200 > > >> I'm not really sure if or how many packets to upper layers buffer. >> > > This is determined by ->tx_queue_len, so whatever value is being > set for ATM network devices is what the core will use for backlog > limiting while the device's TX queue is stopped. I tried varying tx_queue_len by 10, 100, and 1000x, but it didn't seem to help much. Whenever the atm dev called netif_wake_queue() it seems like the driver still starves for packets and still takes time to get going again. It seem like when the driver calls netif_wake_queue() it's TX hardware queue is nearly full, but it has space to accept new packets. The TX hardware queue has time to empty, devices starves for packets(goes idle), then finally a packet comes in from the upper networking layers. I'm not really sure at the moment where the problem lies to my maximum throughput dropping. I did try changing sk_sndbuf to 256K but that didn't seem to help either. -- Karl