From owner-freebsd-hackers Sat Apr 13 20:52:09 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id UAA19413 for hackers-outgoing; Sat, 13 Apr 1996 20:52:09 -0700 (PDT) Received: from Root.COM (implode.Root.COM [198.145.90.17]) by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id UAA19406 for ; Sat, 13 Apr 1996 20:52:05 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by Root.COM (8.7.5/8.6.5) with SMTP id UAA02955; Sat, 13 Apr 1996 20:51:30 -0700 (PDT) Message-Id: <199604140351.UAA02955@Root.COM> X-Authentication-Warning: implode.Root.COM: Host localhost [127.0.0.1] didn't use HELO protocol To: peter@nmti.com (Peter da Silva) cc: hackers@freebsd.org Subject: Re: Pentium fast copy? In-reply-to: Your message of "Sat, 13 Apr 1996 20:52:50 CDT." <9604140152.AA14757@sonic.nmti.com.nmti.com> From: David Greenman Reply-To: davidg@Root.COM Date: Sat, 13 Apr 1996 20:51:30 -0700 Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk >The following quote from a paper (sorry, I don't know what the paper is >offhand) appeared on the Firewalls mailing list. What's FreeBSD like on >this front? > > Our results show that none of the systems adequately delivers the > Pentium's memory write performance. For example, the Pentium can > copy data at over 160 megabytes/second using a prefetching copy > routine, yet none of the systems we tested have implemented such a > routine. As described below, the prefetching routines address the > fact that the Pentium does not have a write-allocate cache. > Without this optimization, the same routines copy data at about 40 > megabytes/second. This is a quote from the Usenix '95 paper comparing several PC operating systems, FreeBSD 2.0.5R being one of them. The bottom line is that we are working on improving this, but some of the "improvements" were recently found to be pessimizations in real-world situations. Not much more to say at this point. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project