Re: [RFC][PATCH] cutting up struct kernel_stat into cpu_stat

[Albert D. Cahalan]

Zach Brown writes:

> The attached patch-in-progress removes the per-cpu statistics from
> struct kernel_stat and puts them in a cpu_stat structure, one per cpu,
> cacheline padded.  The data is still coolated and presented through
> /proc/stat, but another file /proc/cpustat is also added.  The locking
> is as nonexistant as it was with kernel_stat, but who cares, they're
> just fuzzy stats to be eyeballed by system tuners :).

Hey! The lack of atomicity causes "top" to do one of 3 things
for the idle time report, depending on the version:

1. negative numbers
2. wrap-around (42000000.00% idle)
3. truncate to zero (the numbers don't add up)

This is because top sees the idle time run backwards for a moment.