Re: APM killing low-latency performance on BX mainboard (we need a method to disable it dynamically)

Michael K. Johnson (johnsonm@redhat.com)
Wed, 10 Nov 1999 19:05:11 -0500


Benno Senoner writes:
>Now my question: in order to achieve best low-latency performance, we
>need a way to disable APM on problematic boxes, but without recompiling
>the kernel.

That sounds like a statement, not a question. :-)

>my proposals:
>make a sysctl ( or is this already implemented) to disable APM at
>runtime
>or: make a kernel commandline boot option which allows to disable
>APM at boottime, just like when the kernel detects that it is running on
>a SMP box.

We (Red Hat) did not include apm in our default kernels until there was
a way to disable it on the kernel command line. Just use "apm=off".
For what it's worth, a search for "apm" in our knowledgebase finds that
information. Unfortunately, Documentation/kernel-parameters.txt does
not list the possible values, so you couldn't have found it there.
However, arch/i386/kernel/apm.c:apm_setup() is where the parsing is
done.

Hope that helps,

michaelkjohnson

"Magazines all too frequently lead to books and should be regarded by the
prudent as the heavy petting of literature." -- Fran Lebowitz
Linux Application Development http://people.redhat.com/johnsonm/lad/

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