Re: Solved with MTRR was: ISSUE: very slow (factor 100) 4-way 16GByte server, with 2.4.2

[David Wragg]

Robert Suetterlin <[e-mail]> writes:
> 2. I was not allowed to do `base=0 size=0x400000000
> type=write-back`, because of the overlap with the memory range at
> base=0x0fb000000. 

/proc/mtrr does allow overlapping regions in some cases, but the
conditions turned out to be stricter than I remembered.  You have to
create the enclosing range first, which makes the facility useless in
this case (perhaps in all potentially useful cases).

> So what I do is only disable 3-7, and then
> base=0x400000000 size=0x400000000.

Yes, that solution should be safe.