Re: Help understanding slow down

Phy Prabab
2004-05-24T08:00:13Z

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Andrew,

I have turned HT off in the bios (caused non
deterministic performance) and I did not configure the
kernel for SMT. Additionally, looking at dmesg shows
no idle-poll (and I do not boot the kernel with
idle-poll).
Should I post my config for this kernel?

Thank you for your time.
Phy
--- Andrew Morton <akpm@osdl.org> wrote:
> Phy Prabab <phyprabab@yahoo.com> wrote:
> >
> > Okay, here is the output:
> >
> > 317955 total
> > 0.1302
> > 263633 poll_idle
> > 4545.3966
> > 6764 do_page_fault
> > 5.1951
> > 3650 kmap_atomic
>
> It's strange that you appear to be using
> poll_idle(). Maybe it's an error
> in the profiler - it sometimes makes mistakes in
> identifying small
> functions.
>
> But if you _are_ using poll_idle() and if your CPU
> is hyperthreaded then
> yes, one "CPU" is going to take a performance hit
> from the "idle" one.
>
> Is your CPU hyperthreaded? (cat /proc/cpuinfo)
>
> Are you booting with "idle=poll"? Do `dmesg -s
> 1000000 | grep idle'.
>

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