From mboxrd@z Thu Jan 1 00:00:00 1970 From: linas@austin.ibm.com (Linas Vepstas) Subject: Re: [PATCH 2/4]: powerpc/cell spidernet low watermark patch. Date: Fri, 18 Aug 2006 14:23:56 -0500 Message-ID: <20060818192356.GD26889@austin.ibm.com> References: <20060811170337.GH10638@austin.ibm.com> <20060811170813.GJ10638@austin.ibm.com> <1155771820.11312.116.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Jens Osterkamp , James K Lewis , Arnd Bergmann Return-path: Received: from e32.co.us.ibm.com ([32.97.110.150]:52120 "EHLO e32.co.us.ibm.com") by vger.kernel.org with ESMTP id S932483AbWHRTX6 (ORCPT ); Fri, 18 Aug 2006 15:23:58 -0400 To: Benjamin Herrenschmidt Content-Disposition: inline In-Reply-To: <1155771820.11312.116.camel@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Aug 17, 2006 at 01:43:40AM +0200, Benjamin Herrenschmidt wrote: > > Sounds good (without actually looking at the code though :), that was a > long required improvement to that driver. Also, we should probably look > into using NAPI polling for tx completion queue as well, no ? Just for a lark, I tried using NAPI polling, while disabling all TX interrupts. Performance was a disaster: 8Mbits/sec, fom which I conclude that the tcp ack packets do not flow back fast enough to allw reliance on NAPI polling for transmit. I was able to get as high as 960 Mbits/sec in unusal circumstances, at 100% cpu usage. Oprofile indicates that the next major improvement would be to add scatter/gather, which I'll take a shot at next week, if I don't get interrupted. However, I'm getting interrupted a lot these days. --linas