reassign 509215 linux-2.6
thanks
Keith Godfrey wrote:
>
> Hardware: Dell Optiplex
> CPU: Core 2 quad
> OS: Lenny - fresh install ~Dec 15th
>
> Testing configuration and report:
> I have a pthreads based scientific application that uses ~170% and 250% CPU
> usage when running 2 and 3 threads, respectively. This behavior has been
> consistent on several systems, including MacOS and a previous version of
> Lenny. CPU usage was measured using 'top'.
>
> On the freshly installed Lenny, 'top' reported between 70%-105% usage for
> both 2 and 3 threads. The time required for the application to complete was
> comparable to runtimes on MacOS and a previous version of Lenny (all using
> the same or similar CPUs).
>
> I compiled a new kernel (2.6.27.10), basing it the config stored in /boot,
> incorporating minor additional changes. Under the newly compiled kernel,
> 'top' appears to report correct CPU usage. Application runtime remains the
> same.
>
> It apperas that 'top' is reporting incorrect CPU usage on the default kernel.
> It is also possible that the multi-threading doesn't speed anything up in
> this application (very possible) and that the default kernel wasn't properly
> handling the threads, whereas 'top' is OK.
top parses /proc/stat, so it might either be that the data from it
is inconsistent in the 2.6.26 kernel or that top fails to parse
the output properly.
Could you compare the content of /proc/stat from both kernels?
Cheers,
Moritz
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