> I was investigating why sometimes in top I see idle % like
> 9384729374923.43%. It was caused by idle count in /proc/stat
> going backward sometimes.
Thanks for tracking down this bug.
> It can be fixed for SMP:
> * add spinlock
> or
> * add per_cpu_idle, account it too at timer/APIC int
> and get rid of idle % calculations for /proc/stat
>
> As a user, I vote for glitchless statistics even if they
> consume extra i++ cycle every timer int on every CPU.
Same for me. The last option is probably easiest to implement
and cheapest at run time. The extra "cost" will approach zero
once somebody takes the time to put the per-cpu stats on per
cpu cache lines, which I'm sure somebody will do once we have
enough per-cpu stats ;)
cheers,
Rik
-- http://www.linuxsymposium.org/2002/ "You're one of those condescending OLS attendants" "Here's a nickle kid. Go buy yourself a real t-shirt"http://www.surriel.com/ http://distro.conectiva.com/
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