Messages in this thread |  | | Date | Mon, 26 Nov 2001 22:09:02 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: [PATCH] Scalable page cache |
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hm, as far as i can see, your patch dirties both cachelines of the target struct page on every lookup (page_splay_tree_find()), correct? If correct, is this just an implementational thing, or something more fundamental?
i've been thinking about getting rid of some of the cacheline dirtying in the page lookup code, ie. 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)
this would have the benefit of not touching the cacheline while doing a simple read(), if the referenced bit is still set. (which is not cleared too eagerly in most no-VM-pressure cases.) And it should not be a problem that this is not race-free - missing to set the referenced bit is not a big failure.
Ingo
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