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Hi,<br>
<br>
Maxwell Spangler wrote:
<blockquote cite="mid:1279575750.29339.35.camel@localhost.localdomain"
type="cite">
<pre wrap="">On Mon, 2010-07-19 at 15:32 -0600, Jim Ockers wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi CLUEbies,
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:
Intel AMD
2.4 fast fast
2.6 slow fast
</pre>
</blockquote>
<pre wrap=""><!---->
This small bit of data suggests that the 2.6 kernel can run as fast as
the 2.4 but that something about the 2.6 + Intel P4 hardware combination
is slow.
</pre>
</blockquote>
Yes, that is exactly what we have determined.<br>
<blockquote cite="mid:1279575750.29339.35.camel@localhost.localdomain"
type="cite">
<pre wrap="">Can you run the same test on a variety of Intel and AMD chips to see if
a pattern develops? There might be other AMD chips that suffer as well
as other Intel chips that are successful. Comparing the differences in
chip features might point to why your results here are problematic.
</pre>
</blockquote>
I think we've established the pattern because it seems to affect all
Intel P4s running that particular kernel. When we use a stock CentOS
kernel (which doesn't have our custom IDE and network card driver
hacks^H^H^H^H^Hmodifications and other custom settings, then that
hardware is "fast." When we use our custom kernel, it's slow only on
Intel P4.<br>
<blockquote cite="mid:1279575750.29339.35.camel@localhost.localdomain"
type="cite">
<pre wrap="">
Also, were there any clues in the results of the time command's output?
Any big differences on the level of what time was being used: user vs
sys?
</pre>
</blockquote>
Regardless of how long the dd test takes to return, or if the system is
"fast" or "slow," it is almost all sys time that is used. The "user"
time is negligible.<br>
<br>
Jim<br>
<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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