Messages in this thread | | | From | Denis Vlasenko <> | Subject | Re: [RFC][PATCH] iowait statistics | Date | Wed, 15 May 2002 18:17:22 -0200 |
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On 15 May 2002 12:03, Rik van Riel wrote: > > 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.
I think two patches for same kernel piece at the same time is too many. Go ahead and code this if you want.
> 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 ;)
I thought about that too: per_cpu_xxx[cpu] -> per_cpu[cpu].xxx type thing. -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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