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Re: event counting vs. the cache

On Thu, Jan 17, 2013 at 03:43:13PM -0600, David Young wrote:
> 2) Split all counters into two parts: high-order 32 bits, low-order 32
>    bits.  It's only necessary to touch the high-order part when the
>    low-order part rolls over, so in effect you split the counters into
>    write-often (hot) and write-rarely (cold) parts.  Cram together the
>    cold parts in cachelines.  Cram together the hot parts in cachelines.
>    Only the hot parts change that often, so the ordinary footprint of
>    counters in the cache is cut almost in half.

That means have to have special code to read them in order to avoid
having 'silly' values.


David Laight:

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