Re: Is there a way to obtain a machine's cache line size?

[Paul Koning <paul_koning%dell.com@localhost>]

On Jan 20, 2011, at 3:06 PM, Peter Seebach wrote:

> In message <145C3AC8-317E-4D8B-B696-19824A6B81AE%dell.com@localhost>, Paul 
> Koning writes:
>> On Jan 20, 2011, at 2:47 PM, der Mouse wrote:
>>>> I see there is a compile time constant CACHE_LINE_SIZE in
>>>> <sys/param.h> which currently seems to be always be set to 64, but
>>>> I'm pretty certain that is not necessarily a correct value.
> 
>>> You are correct; to cite the one example I currently have swapped into
>>> my brain, the Super-H used in the Dreamcast has 32-byte cache lines
>>> (true of the I-cache and D-cache both).
> 
>> I'm curious why non-kernel components would care.
> 
> Look at the output of lmbench.  Empirically, there are real-world performance
> effects in some boundary cases.
> 
> Some people care about performance enough to tune for stuff like this.

Ok.  So I guess what's really needed is the ability to ask about the cache 
structure: levels, sizes, line sizes... the "config" registers in the MIPS 
coprocessor zero make a nice example.

        paul