From owner-freebsd-net Fri Oct 19 18:41:35 2001 Delivered-To: freebsd-net@freebsd.org Received: from inje.iskon.hr (inje.iskon.hr [213.191.128.16]) by hub.freebsd.org (Postfix) with ESMTP id 15AC937B407 for ; Fri, 19 Oct 2001 18:41:31 -0700 (PDT) Received: from tel.fer.hr (zg06-007.dialin.iskon.hr [213.191.148.8]) by mail.iskon.hr (8.11.4/8.11.4/Iskon 8.11.3-1) with ESMTP id f9K1fSR16241; Sat, 20 Oct 2001 03:41:28 +0200 (MEST) Message-ID: <3BD0D653.EDC5EF8E@tel.fer.hr> Date: Sat, 20 Oct 2001 03:41:40 +0200 From: Marko Zec X-Mailer: Mozilla 4.76 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: Mike Tancsa Cc: freebsd-net@freebsd.org Subject: Re: fxp driver - receive interrupt bundling References: <5.1.0.14.0.20011019211817.05a05890@192.168.0.12> Content-Type: text/plain; charset=iso-8859-2 Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Mike Tancsa wrote: > At 03:16 AM 10/20/2001 +0200, Marko Zec wrote: > >It doesn't matter how many fxp cards you have installed - if your box acts > >as a > >server than most probably you can leave INT_DELAY at default value (Intel > >proposes 0x600, but I think 0x400 would be more appropriate). > > > >If you use your multi-fxp-card BSD box as a router, than the microcode will > >impose additional delay *twice* (once in each direction), so in that case the > >default value of 0x600 might be too high for achieving full 100 megE > >throughput, because of TCP windowing scheme having to wait for ACK frames, > >which will be held in fxp receive buffers too long. On the other hand, setting > >INT_DELAY too low minimizes the benefits of bundling interrupts, as fewer > >received frames get "bundled" on a single interrupt. > > > >To summarize: if you are doing any routing (or bridging as I do), find the > >best > >value for INT_DELAY for your specific environment experimentally, it should be > >definitely smaller than or equal to 0x400. If you don't do packet forwarding > >between fxp interfaces, use the defaults. > > Thanks! This is for a router pushing upwards of 20Mb/s with about 110K > routes on 4 interfaces. I will try and experiment a bit on my test setup > first to see what works best. Nice - I'd be glad if you let us know the details after you complete the experiments. Probably you could try tweaking the BUNDLE_MAX as well, if it is supported by your fxp chipset - on my cards it is not, unfortunately. If you experience high traffic volumes, than having BUNDLE_MAX restricted to only 6 frames (default) can be somewhat unnecessary limitating. Marko To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message