From owner-freebsd-stable Tue Dec 15 08:57:32 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id IAA19362 for freebsd-stable-outgoing; Tue, 15 Dec 1998 08:57:32 -0800 (PST) (envelope-from owner-freebsd-stable@FreeBSD.ORG) Received: from alpha.xerox.com (alpha.Xerox.COM [13.1.64.93]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id IAA19346; Tue, 15 Dec 1998 08:57:31 -0800 (PST) (envelope-from fenner@parc.xerox.com) Received: from crevenia.parc.xerox.com ([13.2.116.11]) by alpha.xerox.com with SMTP id <55530(5)>; Tue, 15 Dec 1998 08:57:24 PST Received: from localhost by crevenia.parc.xerox.com with SMTP id <177535>; Tue, 15 Dec 1998 08:57:14 -0800 To: Michael Robinson cc: fenner@parc.xerox.com, freebsd-net@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: Re: MLEN < write length < MINCLSIZE "bug" In-reply-to: Your message of "Tue, 15 Dec 98 07:55:17 PST." <199812151555.PAA07456@netrinsics.com> Date: Tue, 15 Dec 1998 08:42:29 PST From: Bill Fenner Message-Id: <98Dec15.085714pst.177535@crevenia.parc.xerox.com> Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In message <199812151555.PAA07456@netrinsics.com> you write: >Together, these performance optimizations at different >levels of abstraction can interact badly, under a particular set of >circumstances, but is that really a bug, per se? Ok, it's a performance problem, which was introduced by a performance enhancement. Therefore, it's a bug in the original enhancement. =) >It seems that we only get the "parallelism" if the write length is more >than one mbuf and less than two. You get it also if it's more than the length of a cluster (and particularly multiples of the length of a cluster, e.g. a 64k write). >Is there any documentation on why MINCLSIZE is currently set to the value it >is? Not that I know of, but I can't say for sure that there's not something in the 4.4 daemon book. You know what the main tradeoff is of reducing MINCLSIZE (and there are some subtle ones too - set your socket buffer to 64k and start writing in 120-byte chunks and see when the socket buffer fills up). Bill To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message