From owner-freebsd-current Tue May 7 11:49:11 1996 Return-Path: owner-current Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id LAA24734 for current-outgoing; Tue, 7 May 1996 11:49:11 -0700 (PDT) Received: from ormail.intel.com (ormail.intel.com [134.134.192.3]) by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id LAA24729 for ; Tue, 7 May 1996 11:49:09 -0700 (PDT) Received: from ichips.intel.com (ichips.intel.com [134.134.50.200]) by ormail.intel.com (8.7.4/8.7.3) with ESMTP id LAA15961; Tue, 7 May 1996 11:48:32 -0700 (PDT) Received: from pdx202 by ichips.intel.com (8.7.4/jIII) id LAA03457; Tue, 7 May 1996 11:45:17 -0700 (PDT) Message-Id: <199605071845.LAA03457@ichips.intel.com> To: asami@cs.berkeley.edu (Satoshi Asami) cc: bde@zeta.org.au, current@freebsd.org, nisha@cs.berkeley.edu, marc@bowtie.nl, ken@area238.residence.gatech.edu, wollman@lcs.mit.edu, pattrsn@cs.berkeley.edu, culler@cs.berkeley.edu Subject: Re: more on fast bcopy In-reply-to: Your message of "Tue, 07 May 1996 06:06:09 PDT." <199605071306.GAA04277@silvia.HIP.Berkeley.EDU> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Date: Tue, 07 May 1996 11:48:28 -0700 From: Wayne Scott Sender: owner-current@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > Yes, indeed, this is very interesting. I guess whatever I'm doing > with all this is going to be moot once we all move to P6's. ;) > > By the way, I assume the external clock of the 200MHz P6 is 66MHz, is > this correct? The memory copy speed of this machine seems to be > slower than the Triton-based P5-133 that we have (see below). Do you > know where the "B-step" Orion stands on the maturity curve, in terms > of memory access speed? The problem is that I gave you numbers on a lower performance desktop machine. On a high performance box with 4-way interleaved memory I get the following: size bandwidth 32 46.376812 MB/s 64 43.243243 MB/s yes this dip is expected 128 46.376812 MB/s 256 57.142857 MB/s 512 64.000000 MB/s 1024 66.666667 MB/s 2048 69.565217 MB/s 4096 69.565217 MB/s 8192 71.111111 MB/s When I first ran then benchmark the results were toggling between 66 MB/s and 80 MB/s. The problem was that the benchmark is too fast for gettimeofday to return accurate numbers. Increasing the size of the buffer to be copied from 4 MBs to 32 MBs helpped alot. (For those short on memory just put a loop around the calls to bcopy to make the time longer.) I suspect this problem was occuring with luke's Pentium number. -Wayne Wayne Scott MD6 Architecture wscott@ichips.intel.com Work #: (503) 264-4165 Disclaimer: All views expressed are my own opinions, and not necessarily those of Intel Corporation.