Re: Help understanding slow down

[Andrew Morton]

Phy Prabab <phyprabab@xxxxxxxxx> 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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