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

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Date:	Wed, 12 Dec 2007 13:54:41 -0500
From:	"David P. Reed" <dpreed@...d.com>
To:	Török Edwin <edwintorok@...il.com>
CC:	Rene Herman <rene.herman@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>, pavel@....cz,
	andi@...stfloor.org, rol@...917.net,
	Krzysztof Halasa <khc@...waw.pl>, david@...idnewall.com,
	hpa@...or.com, john@...ffel.org, linux-os@...logic.com
Subject: Re: [RFT] Port 0x80 I/O speed

I have been having a fun time testing this on my AMD64x2 system.

Since out's to port 80 hang the system hard after a while, I can run a 
test just after booting, but the next run will typically hang it.

I did also test two ports thought to be unused.   They do *not* hang the 
system.  Thus apparently there is some device responding to port 80!

Running the (slightly modified to test 3 ports instead of just port 80) 
test when the CPU is running at 800 MHz, here's what I get for port 80 
and port ec and port ef.

port 80:   cycles: out 1430, in 792
port ef:    cycles: out 1431, in 1378
port ec:   cycles: out 1432, in 1372

[Note: port 80, when it doesn't hang, which is very often, responds to a 
read twice as fast as a port which is "not there".   Typically though, 
the second time I run the test, the system freezes solid.  Seems like 
evidence of a present device, not a missing one.  Also, port 80 responds 
when booted with acpi=off, but never seems to hang - sounds like ACPI 
causes it to be active in some way]
----------------------------

System info:  HP Pavilion dv9000z laptop (AMD64x2)

PCI bus controller is nVidia MCP51.
/proc/cpuinfo

processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 72
model name      : AMD Turion(tm) 64 X2 Mobile Technology TL-60
stepping        : 2
cpu MHz         : 800.000
cache size      : 512 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 2
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext 
fxsr_opt rdtscp lm 3dnowext 3dnow rep_good pni cx16 lahf_lm cmp_legacy 
svm extapic cr8_legacy
bogomips        : 1608.35
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

processor       : 1
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 72
model name      : AMD Turion(tm) 64 X2 Mobile Technology TL-60
stepping        : 2
cpu MHz         : 800.000
cache size      : 512 KB
physical id     : 0
siblings        : 2
core id         : 1
cpu cores       : 2
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext 
fxsr_opt rdtscp lm 3dnowext 3dnow rep_good pni cx16 lahf_lm cmp_legacy 
svm extapic cr8_legacy
bogomips        : 1608.35
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

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