Re: [FAQ?] More ram=less performance (maximum cacheable RAM)

Richard Gooch
2001-08-21T19:57:55Z

Luca Montecchiani writes:
> I've recently updated my K6-2 from 128 to 256mbytes (2x128 pc133 dimms)
> compiling kernel take now 13 minutes instead of 9 minutes :(
>
> Ram is so cheap and socket7 is far from the death, time for a FAQ?
>
> Here some description from http://9-muses.com/freak/reviews/super7.shtml :
> The Level2 Cache determines the board's maximum cacheable RAM.
> Boards equipped with 512k can cache up to 128MB of RAM while
> those equipped with 1MB can handle up to 256MB of RAM. If you're using all
> of the RAM cacheable by the the L2 cache, performance is enhanced. Once you
> go above the maximum cacheable RAM, performance is lost. What this means to
> you is the more cache the better. For some users, 64MB or even 128MB of RAM
> is enough, but who knows, somewhere down the road, you might want to upgrade
> to 256MB. It's nice to know your board can handle the extra memory without
> worrying about losing performance.
>
> More technical information can be found here :
> http://www.pcguide.com/ref/mbsys/cache/char_Cacheability.htm
>
> Patch and other info about non cacheable ram here :
> http://www.keryan.org/brad/slram/

Er, are you sure about this? The problem isn't the size of your cache,
it's the size of your TAG RAM. That's a different beast.

Regards,

Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca