Robert Love <rml@tech9.net> wrote:
> On Mon, 2001-12-10 at 03:00, Stevie O wrote:
>
> > For the n-way associative deal:
>
> If the cache is n-way associative, it can store n lines at each
> mapping. So even though two virtual addresses map to the same cache
> line, they can both be stored. Of course, if you have k addresses such
> that k>n, then you reach the same problem as direct map (the case where
> n=1) caches.
That is a good explanation. Related would be the TLB and its
thrashing...
> To reiterate, the point of coloring would be to prevent the case of
> multiple addresses mapping to the same line.
Can you get colo[u]red memory from user-space? This would be really
useful for certain memory intensive applications (I'm thinking of
large FFT users like mprime/ARMprime here)
-- Nick Craig-Wood ncw@axis.demon.co.uk> Let me give you a > real-life example. We recently have been trying to color the kernel > stack. If every process's stack lies at the same address (let alone the > same page multiple and offset), then they all map to the same place in > the cache and we can effectively only cache one of them (and > subsequently cache miss on every other access). If we "color" the > location of the stack, we make sure they don't all map to the same > place. This obviously involves some knowledge of the cache system, but > it tends to be general enough that we can get it right for all cases. > > If you are _really_ interested in this, an excellent and very thorough > book is UNIX Systems for Modern Architectures: Symmetric Multiprocessing > and Caching for Kernel Programmers, by Curt Schimmel. > > Robert Love > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to > 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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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:17 EST