Re: [PATCH] Scalable page cache

Andrew Morton (akpm@zip.com.au)
Mon, 26 Nov 2001 11:45:36 -0800


"David S. Miller" wrote:
>
> From: Ingo Molnar <mingo@elte.hu>
> Date: Mon, 26 Nov 2001 22:09:02 +0100 (CET)
>
> something like this:
>
> - #define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
> + #define SetPageReferenced(page) \
> + if (!test_bit(PG_referenced), &(page)->flags) \
> + set_bit(PG_referenced, &(page)->flags)
>
> On some platforms all the {test_,}{clear,change,set}_bit() ops give
> you this cache behavior. How hard would it be to make ix86 act
> similarly?

It would be nice to have a full complement of non-atomic
bitops. At present we have __set_bit, but no __clear_bit, etc.

So we often do buslocked RMW's in places where it's not needed.

-
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