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<font size="+1"><tt>Hi CLUEbies,<br>
<br>
I have a curious problem. We compiled a custom 2.6 Linux kernel for an
embedded platform. The target hardware is Intel P4 or AMD. The
hardware used to run a 2.4 Linux kernel. Here is the fast/slowness
matrix:<br>
<br>
Intel AMD<br>
2.4 fast fast<br>
2.6 slow fast<br>
<br>
Of course you want to know what "slow" means. We have a test which we
use to expose thermal throttling of the Intel CPU, since without
"special" software there is no easy way to tell if the CPU is
undergoing thermal throttling. Here is the test:<br>
<br>
[root]# time dd if=/dev/zero of=/dev/null bs=1024k count=100000<br>
100000+0 records in<br>
100000+0 records out<br>
104857600000 bytes (105 GB) copied, 6.60495 seconds, 15.9 GB/s<br>
<br>
On a "fast" system (per the matrix above) that command returns in about
2-2.5 seconds. On a "slow" system (even without any thermal
throttling) that command returns in 7-9 seconds. With thermal
throttling it is much worse, anywhere from 10-180 seconds depending on
the level of thermal throttling.<br>
<br>
Here is the cpuinfo for the affected processor:<br>
<br>
[root]# cat /proc/cpuinfo<br>
processor : 0<br>
vendor_id : GenuineIntel<br>
cpu family : 15<br>
model : 4<br>
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz<br>
stepping : 1<br>
cpu MHz : 2992.760<br>
cache size : 1024 KB<br>
physical id : 0<br>
siblings : 2<br>
core id : 0<br>
cpu cores : 1<br>
fdiv_bug : no<br>
hlt_bug : no<br>
f00f_bug : no<br>
coma_bug : no<br>
fpu : yes<br>
fpu_exception : yes<br>
cpuid level : 5<br>
wp : yes<br>
flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
constant_tsc pni monitor ds_cpl cid xtpr<br>
bogomips : 5987.38<br>
<br>
<br>
I could attach or send the .config file from which the 2.6 kernel is
compiled but it is big and noisy. Does anyone have suggestions about
what CPU options we should try to change in the kernel configuration to
make it "fast" with a 2.6 kernel on this Intel P4 CPU? There is a
dizzying number of config categories that might be related, in
categories like these:<br>
<br>
# Processor type and features<br>
# ACPI (Advanced Configuration and Power Interface) Support<br>
# CPU Frequency scaling<br>
# CPUFreq processor drivers<br>
<br>
We need to fix this because it is causing a lot of our systems to be
unnecessarily slow. Any ideas, anyone? What other information might
you need about this?<br>
<br>
Thanks,<br>
Jim<br>
</tt></font>
<pre class="moz-signature" cols="72">--
Jim Ockers, P.Eng. (<a class="moz-txt-link-abbreviated" href="mailto:ockers@ockers.net">ockers@ockers.net</a>)
Contact info: <a class="moz-txt-link-freetext" href="http://www.ockers.ca/pason.html">http://www.ockers.ca/pason.html</a>
</pre>
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