From owner-freebsd-net Thu Oct 11 18:33:47 2001 Delivered-To: freebsd-net@freebsd.org Received: from iguana.aciri.org (iguana.aciri.org [192.150.187.36]) by hub.freebsd.org (Postfix) with ESMTP id 0335337B401 for ; Thu, 11 Oct 2001 18:33:46 -0700 (PDT) Received: (from rizzo@localhost) by iguana.aciri.org (8.11.3/8.11.1) id f9C1Ubw15419; Thu, 11 Oct 2001 18:30:37 -0700 (PDT) (envelope-from rizzo) From: Luigi Rizzo Message-Id: <200110120130.f9C1Ubw15419@iguana.aciri.org> Subject: Re: strange results with increased net.inet.ip.intr_queue_maxlen In-Reply-To: <200110120116.f9C1GEv18196@arch20m.dellroad.org> from Archie Cobbs at "Oct 11, 2001 6:16:14 pm" To: archie@dellroad.org (Archie Cobbs) Date: Thu, 11 Oct 2001 18:30:37 -0700 (PDT) Cc: mike@sentex.net, rizzo@aciri.org, freebsd-net@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL43 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 > > from pinging the other side of the OC-3 or ethernet connection and > > measuring the response time, how can I see how much latency is added by > > increasing these buffers ? of course the latency increase depends on how full are the buffers, and the worst case is easier to determine by back-of-the-envelope calculations: queue_slots * max_pkt_size / bottleneck_link_speed e.g. if you have 100 slots and an MSS of 1500 and a 10Mbit bottleneck you are adding (100*1500*8 / 10000000) = 120ms latency. cheers luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message