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

From: Bauke Jan Douma
Date: Sat Dec 22 2007 - 17:27:21 EST


Rene Herman wrote on 12-12-07 00:31:
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.

Compiled as you wished.
And here are the results from 10 iterations...:

cycles: out 1965, in 1263
cycles: out 1968, in 1251
cycles: out 1957, in 1257
cycles: out 1992, in 1253
cycles: out 1959, in 1248
cycles: out 1965, in 1264
cycles: out 1957, in 1256
cycles: out 1959, in 1248
cycles: out 1962, in 1298
cycles: out 1962, in 1275

Linux skyscraper 2.6.23.11 #1 SMP Sun Dec 16 11:54:12 CET 2007 i686 GNU/Linux

32bits system

processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 Quad CPU @ 2.40GHz
stepping : 7
cpu MHz : 2400.182
cache size : 4096 KB
physical id : 0
siblings : 4
core id : 0
cpu cores : 4
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr s
bogomips : 4802.73
clflush size : 64

processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 Quad CPU @ 2.40GHz
stepping : 7
cpu MHz : 2400.182
cache size : 4096 KB
physical id : 0
siblings : 4
core id : 1
cpu cores : 4
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr s
bogomips : 10614.49
clflush size : 64

processor : 2
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 Quad CPU @ 2.40GHz
stepping : 7
cpu MHz : 2400.182
cache size : 4096 KB
physical id : 0
siblings : 4
core id : 2
cpu cores : 4
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr s
bogomips : 4800.17
clflush size : 64

processor : 3
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 Quad CPU @ 2.40GHz
stepping : 7
cpu MHz : 2400.182
cache size : 4096 KB
physical id : 0
siblings : 4
core id : 3
cpu cores : 4
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr s
bogomips : 4800.17
clflush size : 64

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