Re: Notebooks

Linus Torvalds (torvalds@transmeta.com)
Tue, 18 Aug 1998 23:18:40 -0700 (PDT)


On Wed, 19 Aug 1998, Andi Kleen wrote:
>
> My theory is that it is caused by better cache line usage. In the bulk
> transfer case most packets have the same size (device MTU), and then
> the cache wasn't effectively used. slab fixes that. Also the other
> sk_buff code has been simplified which should speed it up too.

Hmmm.. Slab does cache-align the allocations, something that the original
code didn't try to do. The old kmalloc() tried to be space-efficient even
if it meant returning an allocation at even just a 4-byte boundary, which
might have been a mistake.

I don't think the colouring should matter - at least I've never really
seen any of that on my machines. But I've been playing with PPro's and
PII's, mostly, and I think they are all four-way - if you did your numbers
on a Pentium (no-MMX) it's only two-way set associative, and cache
colouring may be more of an issue for you.

Linus

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