RE: free bootmem feedback patch

Luck, Tony
2004-08-06T20:09:34Z

>I'll go ahead and create a macro for the non-atomic bit clear. Perhaps
>call it "ClearPageReservedNoAtomic" instead of "BootClearPageReserved"?

That looks like a more meaningful name than my suggestion.

>> Finally you have a magic "16" in the prefetchw() path. Where did
>> it come from, and is it the right number for non-ia64 machines?
>
>My bad for not explaining that. In my limited testing of this particular
>number it seemed to be the sweet spot for prefetching. I think it is a
>good number for all architectures because 32 bit architectures won't
>need the speed boost as much as 64 bit architectures. They are not
>likely to have > 4GB memory,, in which case this function's time is
>probably less than 1 second anyway.

There are quite a few x86 boxes running with 16GB ... but the max
is 64GB, which is still below the pain threshold for seeing an
unreasonable delay during this routine ... so I agree that perfect
tuning is irrelevent for 32-bit machines here. You should include
your explanatory paragraph when you post to LKML.

-Tony