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Message-ID: <47615D81.30707@intcomgrp.com>
Date: Thu, 13 Dec 2007 11:27:45 -0500
From: James Kosin <jkosin@...comgrp.com>
To: linux-kernel@...r.kernel.org
Subject: Re: [RFT] Port 0x80 I/O speed
Rene Herman wrote:
> Good day.
>
> Would some people on x86 (both 32 and 64) be kind enough to compile and
> run the attached program? This is about testing how long I/O port access
> to port 0x80 takes. It measures in CPU cycles so CPU speed is crucial in
> reporting.
>
> Posted a previous incarnation of this before, buried in the outb 0x80
> thread which had a serialising problem. This one should as far as I can
> see measure the right thing though. Please yell if you disagree...
>
> For me, on a Duron 1300 (AMD756 chipset) I have a constant:
>
> rene@...e4:~/src/port80$ su -c ./port80
> cycles: out 2400, in 2400
>
> and on a PII 400 (Intel 440BX chipset) a constant:
>
> rene@...p:~/src/port80$ su -c ./port80
> cycles: out 553, in 251
>
> Results are (mostly) independent of compiler optimisation, but testing
> with an -O2 compile should be most useful. Thanks!
>
> Rene.
>
[root@...a jkosin]# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 7
model name : Pentium III (Katmai)
stepping : 3
cpu MHz : 499.156
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca
cmov pat pse36 mmx fxsr sse
bogomips : 996.14
[root@...a jkosin]# ./a.out
cycles: out 683, in 299
[root@...a jkosin]# ./a.out
cycles: out 683, in 299
[root@...a jkosin]# ./a.out
cycles: out 683, in 299
[root@...a jkosin]#
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