Date: Fri, 20 Mar 1998 07:59:02 +1100 (EST) From: Andrew Reilly <reilly@zeta.org.au> To: hasty@rah.star-gate.com Cc: lamaster@george.arc.nasa.gov, freebsd-current@FreeBSD.ORG Subject: Re: Stream_d benchmark... Wow, there really are differences in har dware Message-ID: <199803192059.HAA08094@gurney.reilly.home> In-Reply-To: <199803191010.CAA21492@rah.star-gate.com>
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On 19 Mar, Amancio Hasty wrote: > Function Rate (MB/s) RMS time Min time Max time > Copy: 113.7778 0.1557 0.1406 0.1719 > Scale: 107.7895 0.1565 0.1484 0.1719 > Add: 118.1538 0.2158 0.2031 0.2344 > Triad: 118.1538 0.2213 0.2031 0.2344 >> Soeren Schmidt (sos@FreeBSD.org) wrote: >> > Function Rate (MB/s) RMS time Min time Max time >> > Copy: 117.0286 0.2758 0.2734 0.2812 >> : >> > Triad: 125.3878 0.3917 0.3828 0.4219 >> > > Box 1 is a SuperMicro P6DNE: >> > > Function Rate (MB/s) RMS time Min time Max time >> > > Copy: 60.7395 0.2704 0.2634 0.2832 >> > > Triad: 71.1647 0.3494 0.3372 0.3565 >> >> Typical for Natoma with FP DRAM I would guess. I have to say that these are all really terrible numbers! Does anyone know what the DRAM controller on these motherboards is doing? Posit: A Pentium or Pentium pro memory system is 64 bits wide (8 bytes), clocked at 66MHz, or 15ns/cycle. EDO dram shouldn't have trouble doing four cycle bursts as 4-1-1-1, or perhaps 5-1-1-1: say 120ns/cache line of 32 bytes. That's 265M/s in my book. I assume that the benchmark code for stream is small, sits in the internal cache, and just thrashes through long vectors, which should result in back-to-back cache reads (and writes?) Does anyone know where that factor of two is going? Maybe PC's only get EDO to do -2-2-2? Do any PC chipsets notice sequential address blocks and avoid the unnecessary row address cycles? Seemingly not... -- Andrew "The steady state of disks is full." -- Ken Thompson To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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