From owner-freebsd-current Wed Apr 1 19:39:02 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA06146 for freebsd-current-outgoing; Wed, 1 Apr 1998 19:39:02 -0800 (PST) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from firewall.scitec.com.au (firewall-user@fgate.scitec.com.au [203.17.180.68]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id TAA06137 for ; Wed, 1 Apr 1998 19:38:49 -0800 (PST) (envelope-from john.saunders@scitec.com.au) Received: by firewall.scitec.com.au; id NAA14565; Thu, 2 Apr 1998 13:38:35 +1000 (EST) Received: from mailhub.scitec.com.au(203.17.180.131) by fgate.scitec.com.au via smap (3.2) id xma014560; Thu, 2 Apr 98 13:38:31 +1000 Received: from hydra.scitec.com.au (hydra.scitec.com.au [203.17.182.101]) by mailhub.scitec.com.au (8.6.12/8.6.9) with ESMTP id NAA13612; Thu, 2 Apr 1998 13:38:24 +1000 Received: from scitec.com.au (saruman.scitec.com.au) by hydra.scitec.com.au with ESMTP (1.40.112.8/16.2) id AA003858297; Thu, 2 Apr 1998 13:38:17 +1000 Message-Id: <35230829.78DAA808@scitec.com.au> Date: Thu, 02 Apr 1998 13:38:17 +1000 From: John Saunders Organization: SCITEC LIMITED X-Mailer: Mozilla 4.04 [en] (WinNT; I) Mime-Version: 1.0 To: "Gregory P. Smith" , freebsd-current@FreeBSD.ORG Subject: Re: current-digest V4 #79 References: <199804020201.SAA03945@ryouko.nas.nasa.gov> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Gregory P. Smith wrote: > I think that would violate the Kernel's "never use floating point" rule > because MMX uses the FP registers. (and on Intel's MMX implementation > supposedly has a "large" context switch time between MMX and floating > point mode). How does the kernel's "never use floating point" rule co-exist with the bcopy/bzero/copying/copyout speedups that use the FPU? I've noticed that the GENERIC config disables the bcopy speedup by using flags 0x1 but retains the bzero and copyin/out speedups. I've changed my flags to 0 to enable all speedups and haven't noticed anything bad. You are right that the context switch is likely to be a killer, although it depends on exactly how much the IP checksum can be speeded up. When the numbers are added up it could be a big win for a server. I guess the only way to know is to count those clocks. Cheers. -- +------------------------------------------------------------+ . | John Saunders mailto:John.Saunders@scitec.com.au (Work) | ,--_|\ | mailto:john@nlc.net.au (Home) | / Oz \ | http://www.nlc.net.au/~john/ | \_,--\_/ | SCITEC LIMITED Phone +61 2 9428 9563 Fax +61 2 9428 9933 | v | "By the time you make ends meet, they move the ends." | +------------------------------------------------------------+ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message