Re: [RFT] Port 0x80 I/O speed

[Maxim Levitsky]

On Wednesday 12 December 2007 01:31:18 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@7ixe4:~/src/port80$ su -c ./port80
> cycles: out 2400, in 2400
> 
> and on a PII 400 (Intel 440BX chipset) a constant:
> 
> rene@6bap:~/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.
> 


Sure,

maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1767, in 1147
maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1774, in 1148
maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1769, in 1150
maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1769, in 1150
maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1777, in 1150
maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1766, in 1149
maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1768, in 1148
maxim@MAIN:~/tmp$ sudo ./port800
cycles: out 1765, in 1147


Core 2 Duo system (ICH8/Intel DG965RY motherboard)
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