Messages in this thread | | | Date | Sat, 12 Dec 1998 18:05:08 +1100 | From | Richard Gooch <> | Subject | Re: [NOT_A_BUG] (I think) MTRR nice things... :) |
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Romano Giannetti writes: > Hi all, > > I was trying to x11perf(1) measure the performance boost of my ATI > rage IIC with and without the mtrr aperture > > (0)pern:~/tmp% cat /proc/mtrr > reg00: base=0x00000000 ( 0MB), size= 64MB: write-back, count=1 > reg01: base=0xaf000000 (2800MB), size= 2MB: write-combining, count=2 > > and I did a typing error resulting in reg00 (main memory) being > deleted. Try to guess what happened. System was _really_slow_, much > less than my old 386sx. You could notice almost one second wait > between prompts of shell (bash on vesafb console).
Yeah, I did this once when I was hacking the MTRR code. To my amazement, the system didn't crash. It just was sloooooow.
> Well. I think this is a "so do not do it" thing, but I was really > amazed to see such a _big_ slowdown. Really cache/no cache can do > this difference?
Go ahead: do it. It's quite safe. Just not useful ;-) The slowdown is pretty much what you'd expect. Situation normal. All you did was to disable the cache. Now you know why we pay for caches.
For a comparison, disable the cache(s) in your BIOS setup. Note the slowdown.
Regards,
Richard....
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