Date: Thu, 19 Mar 1998 12:59:00 +1100 From: Bruce Evans <bde@zeta.org.au> To: mrcpu@cdsnet.net, sos@FreeBSD.ORG Cc: current@FreeBSD.ORG Subject: Re: Stream_d benchmark... Wow, there really are differences in hardware Message-ID: <199803190159.MAA04545@godzilla.zeta.org.au>
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>Hmm, Then I should be proud of my noname system (p6/200/128MB 72pEDO): > >Function Rate (MB/s) RMS time Min time Max time >Copy: 117.0286 0.2758 0.2734 0.2812 >Scale: 117.0286 0.2782 0.2734 0.2812 >Add: 130.7234 0.3784 0.3672 0.4141 >Triad: 125.3878 0.3917 0.3828 0.4219 > >So what ?? So someone forgot to ensure that the doubles are aligned. This requires using -malign-double and fixing ld so that it actually works. -malign-double -static gives perfect misalignment here: 0000b070 D _edata <- padding not expected by gcc 0000b074 b _a 00191a74 b _b 00318474 b _c 0049f5d4 B _errno I fudged alignment by adding `static int x;' before the declaration of a[], and NOT using -malign-double. >> I figured that within reason, most mb's would have similar performance, >> but I was wrong. >> >> All boxes are P6-200's, 256MB RAM (all RAM is 60ns FP as far as I know). >> >> 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 >> Scale: 60.8640 0.2719 0.2629 0.3097 >> Add: 70.9688 0.3508 0.3382 0.3602 >> Triad: 71.1647 0.3494 0.3372 0.3565 This seems a bit slow, even with misaligned doubles. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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