From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: NAPI-ized tulip patch against 2.4.20-rc1 Date: Wed, 06 Nov 2002 13:30:56 -0800 Sender: netdev-bounce@oss.sgi.com Message-ID: <3DC98A10.5030407@candelatech.com> References: <3DC8B85B.5050805@candelatech.com> <15817.21170.173913.829498@robur.slu.se> <3DC95631.6030001@candelatech.com> <15817.29109.859144.565330@robur.slu.se> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: "'netdev@oss.sgi.com'" Return-path: To: Robert Olsson Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Robert Olsson wrote: > Ben Greear writes: > I still doubt ;-) > > With e1000 I played with various settings for RX-buffers rather recently > when the 82544 increased the number of available buffers from 256 to 4096. > > And I guess my test looks a bit like yours... Injecting an "overload" of > packets. I found was 256 buffers was the optimum. Approximative of course. It's possible that it is a particular issue with my NICs (Old Phobos 4-port). Phobos folks said the bridge chipset has errata that make it un-suitable for high speeds. And something about a memory divide-by-four error. It may be that the extra buffers help hide the hardware defects in some manner. I was, for instance, seeing cases where packets just dissappeared...and no error counters were being bumped. With the latest kernel drivers, the 570tx NIC seems to have trouble autonegotiating full-duplex again, so I have not been testing with it lately (I think it uses the same bridge chipset anyway.) I will try changing around those numbers again now that I have a baseline to work from. > And as you saw for SMP with recycle it is easy to feed the recycled skb > back to CPU were it was created/processed. Yes, I can see how that would be useful on SMP, so there may be less gain for single-proc systems. I actually am pretty fuzzy on cache-line optimizations and the like... Thanks, Ben -- Ben Greear President of Candela Technologies Inc http://www.candelatech.com ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear