Re: [PATCH] Pentium IV cacheline size.

Mikael Pettersson
2001-10-13T14:17:06Z

On Sat, 13 Oct 2001 12:57:33 +0100, Dave Jones wrote:
>Currently, we're using a L1_CACHE_SHIFT value of 7
>for Pentium 4, which equates to 128 byte cache lines.
>Curious, I dumped the info on the only P4 I could find,
>and noticed they were 64 byte.
>Upon checking the documentation, they're 64 byte there too.
>Is this just a thinko on someones part, or was there a
>rationale behind this that I've not realised ?

According to the P4 and Xeon optimisation manual (#248966-03), the
L1 cache has a 64-byte line size and the L2 cache has a 128-byte
line size. (Page 1-18, Table 1-1.) Perhaps someone just confused
the two, or the distinction wasn't known when the initial P4
support was added to the kernel.

/Mikael