From owner-freebsd-net Sun Aug 27 17: 3:59 2000 Delivered-To: freebsd-net@freebsd.org Received: from khavrinen.lcs.mit.edu (khavrinen.lcs.mit.edu [18.24.4.193]) by hub.freebsd.org (Postfix) with ESMTP id 088B137B42C for ; Sun, 27 Aug 2000 17:03:58 -0700 (PDT) Received: (from wollman@localhost) by khavrinen.lcs.mit.edu (8.9.3/8.9.3) id UAA21054; Sun, 27 Aug 2000 20:03:55 -0400 (EDT) (envelope-from wollman) Date: Sun, 27 Aug 2000 20:03:55 -0400 (EDT) From: Garrett Wollman Message-Id: <200008280003.UAA21054@khavrinen.lcs.mit.edu> To: Ping Yuan Cc: freebsd-net@FreeBSD.ORG Subject: Setting buffer size. In-Reply-To: <20000827174129.15742.qmail@web1607.mail.yahoo.com> References: <20000827174129.15742.qmail@web1607.mail.yahoo.com> Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org < said: > I am now using Freebsd 3.2 as a router. I noticed that > when the router was busy, more packets would be > dropped. This is a fundamental limitation of BSD's network stack and two-level interrupt scheme. More memory will not help; when packets are being dropped, the kernel is already receiving more packets per unit time than it is capable of forwarding. See, for exampl, Jeff Mogul's ``Receive Livelock'' paper. -GAWollman -- Garrett A. Wollman | O Siem / We are all family / O Siem / We're all the same wollman@lcs.mit.edu | O Siem / The fires of freedom Opinions not those of| Dance in the burning flame MIT, LCS, CRS, or NSA| - Susan Aglukark and Chad Irschick To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message