Konstantin Khlebnikov wrote:
Hugh Dickins wrote:
On Fri, 9 Mar 2012, Konstantin Khlebnikov wrote:
Actually __isolate_lru_page() even little bit bigger
I was coming to realize that it must be your page_lru()ing:
although it's dressed up in one line, there's several branches there.
Yes, but I think we can optimize page_lru(): we can prepare ready-to-use
page lru index in lower bits of page->flags, if we swap page flags and split
LRU_UNEVICTABLE into FILE/ANON parts.
I think you'll find you have a clear winner at last, if you just pass
lru on down as third arg to __isolate_lru_page(), where file used to
be passed, instead of re-evaluating it inside.
shrink callers already have the lru, and compaction works it out
immediately afterwards.
No, for non-lumpy isolation we don't need this check at all,
because all pages already picked from right lru list.
I'll send separate patch for this (on top v5 patchset), after meditation =)
Heh, looks like we don't need these checks at all:
without RECLAIM_MODE_LUMPYRECLAIM we isolate only pages from right lru,
with RECLAIM_MODE_LUMPYRECLAIM we isolate pages from all evictable lru.
Thus we should check only PageUnevictable() on lumpy reclaim.
Though we do need to be careful: the lumpy case would then have to
pass page_lru(cursor_page). Oh, actually no (though it would deserve
a comment): since the lumpy case selects LRU_ALL_EVICTABLE, it's
irrelevant what it passes for lru, so might as well stick with
the one passed down. Though you may decide I'm being too tricky
there, and prefer to calculate page_lru(cursor_page) anyway, it
not being the hottest path.
Whether you'd still want page_lru(page) __always_inline, I don't know.
Hugh
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