G3 Upgrade Card - Help with enabling Cache properly

[Tim Seufert]

On Sunday, June 8, 2003, at 07:32  AM, Mike Kimmick wrote:

> L2 cache : 256K unified=A0=A0 <-----I still have orig. cache card =
installed

You should remove it.  It becomes a L3 cache that is smaller than the=20
L2 cache.  Because it is smaller, any memory access that misses in L2=20
will always miss in L3. (*)  A cache which misses on every access does=20=

the exact opposite of enhancing performance; it just adds delay to=20
every memory access.

Another reason to remove it is that typically G3/G4 upgrades are more=20
stable without them on the bus.

As for the l2cr override line in /proc/cpuinfo, it probably means that=20=

you passed the kernel an "l2cr=3D0xsomething" argument.  (which is what=20=

BootX does)


(*) Technically that's not quite true; there are possible cache=20
hierarchies where a smaller L3 could contain data that L2 does not. =20
However for the types of cache in this specific system, it is easily=20
proven that L2 misses will always miss in L3.