Re: Cache incoherencies (WAS: New resources - pls, explain :-( )

Ralf Baechle (ralf@uni-koblenz.de)
Wed, 25 Aug 1999 02:58:36 +0200


> > In order to make something compilable on both coherent and incoherent
> > archs, we should standardize the #define for the cache line size, add a
> > routine/macro to query about the coherency of the bus, and provide a
> > "magic" bit for kmalloc that gives you non cachable space.

A per bus coherency isn't sufficient. There are architectures which can
set cache coherency on a per device base. On SMPs this can avoid a
major amount of cross-CPU invalidates, therefore a good performance gain.
For architectures like this you want to leave the decission to the
driver writer.

Ralf

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