Phoronix benchmarks DF 3.2 vs Ubuntu - question

Alex Hornung alex at alexhornung.com
Fri Jan 4 14:36:28 PST 2013


On 04/01/13 22:24, Alex Hornung wrote:
> Since the L1 cache is (in this and most cases) virtually indexed and
> physically tagged, the fact that the lower (virtual) address bits, used
> for indexing, are the same on dragonfly, means that we hit the
> associativity limit of the cache, while linux is hitting different
> lines/indexes in the cache.

For completeness sake, it might be worth pointing out that it might not
be strictly speaking the associativity limit, but a non-optimal access
pattern to the cache banks or even the RAM banks that make up each cache
bank.

Cheers,
Alex



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