Messages in this thread Patch in this message | | | From | Nikita Danilov <> | Date | Mon, 22 Nov 2004 01:37:29 +0300 | Subject | Re: [PATCH]: 2/4 mm/swap.c cleanup |
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Andrew Morton writes: > Nikita Danilov <nikita@clusterfs.com> wrote: > > > > +#define pagevec_for_each_page(_v, _i, _p, _z) \ > > +for (_i = 0, _z = NULL; \ > > + ((_i) < pagevec_count(_v) && (__guardloop(_v, _i, _p, _z), 1)) || \ > > + (__postloop(_v, _i, _p, _z), 0); \ > > + (_i)++) > > Sorry, this looks more like a dirtyup to me ;)
Don't tell me you are not great fan on comma operator abuse. :)
Anyway, idea is that by hiding complexity it loop macro, we get rid of a maze of pvec-loops in swap.c all alike.
Attached is next, more typeful variant. Compilebootentested.
Nikita.
Add pagevec_for_each_page() macro to iterate over all pages in a pagevec. Non-trivial part is to keep track of page zone and relock zone->lru_lock when switching to new zone.
This simplifies functions in mm/swap.c that process pages from pvec in a batch.
Signed-off-by: Nikita Danilov <nikita@clusterfs.com>
include/linux/pagevec.h | 14 ++++++++ mm/swap.c | 83 ++++++++++++++++++++++++------------------------ 2 files changed, 57 insertions(+), 40 deletions(-)
diff -puN include/linux/pagevec.h~pvec-cleanup include/linux/pagevec.h --- bk-linux/include/linux/pagevec.h~pvec-cleanup 2004-11-21 18:59:59.000000000 +0300 +++ bk-linux-nikita/include/linux/pagevec.h 2004-11-22 01:13:54.000000000 +0300 @@ -83,3 +83,17 @@ static inline void pagevec_lru_add(struc if (pagevec_count(pvec)) __pagevec_lru_add(pvec); } + +struct page *__pagevec_loop_next(struct pagevec *pvec, + struct zone **zone, int *i); + +/* + * Macro to iterate over all pages in pvec. Body of a loop is invoked with + * page's zone ->lru_lock held. This is used by various function in mm/swap.c + * to batch per-page operations that whould otherwise had to acquire hot + * zone->lru_lock for each page. + */ +#define pagevec_for_each_page(pvec, i, page, zone) \ + for ((i) = 0, (zone) = NULL; \ + ((page) = __pagevec_loop_next((pvec), &(zone), &(i))) != NULL; \ + ++ (i)) diff -puN mm/swap.c~pvec-cleanup mm/swap.c --- bk-linux/mm/swap.c~pvec-cleanup 2004-11-21 18:59:59.000000000 +0300 +++ bk-linux-nikita/mm/swap.c 2004-11-22 01:19:17.758782008 +0300 @@ -55,6 +55,39 @@ EXPORT_SYMBOL(put_page); #endif /* + * Helper function for include/linux/pagevec.h:pagevec_for_each_page macro. + * + * Returns @i-th page from @pvec, with page zone locked. @zone points to + * previously locked zone, it's updated (and zone is re-locked) if zone is + * changed. + */ +struct page *__pagevec_loop_next(struct pagevec *pvec, + struct zone **zone, int *i) +{ + struct page *page; + struct zone *next_zone; + struct zone *prev_zone; + + prev_zone = *zone; + if (*i < pagevec_count(pvec)) { + + page = pvec->pages[*i]; + next_zone = page_zone(page); + if (next_zone != prev_zone) { + if (prev_zone != NULL) + spin_unlock_irq(&prev_zone->lru_lock); + *zone = next_zone; + spin_lock_irq(&next_zone->lru_lock); + } + } else { + page = NULL; + if (prev_zone != NULL) + spin_unlock_irq(&prev_zone->lru_lock); + } + return page; +} + +/* * Writeback is about to end against a page which has been marked for immediate * reclaim. If it still appears to be reclaimable, move it to the tail of the * inactive list. The page still has PageWriteback set, which will pin it. @@ -116,19 +149,11 @@ void fastcall activate_page(struct page static void __pagevec_mark_accessed(struct pagevec *pvec) { int i; - struct zone *zone = NULL; - - for (i = 0; i < pagevec_count(pvec); i++) { - struct page *page = pvec->pages[i]; - struct zone *pagezone = page_zone(page); + struct zone *zone; + struct page *page; - if (pagezone != zone) { - if (zone) - local_unlock_irq(&zone->lru_lock); - zone = pagezone; - local_lock_irq(&zone->lru_lock); - } - if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) { + pagevec_for_each_page(pvec, i, page, zone) { + if (!PageActive(page) && PageReferenced(page) && PageLRU(page)){ del_page_from_inactive_list(zone, page); SetPageActive(page); add_page_to_active_list(zone, page); @@ -138,8 +163,6 @@ static void __pagevec_mark_accessed(stru SetPageReferenced(page); } } - if (zone) - local_unlock_irq(&zone->lru_lock); release_pages(pvec->pages, pvec->nr, pvec->cold); pagevec_reinit(pvec); } @@ -322,25 +345,15 @@ void __pagevec_release_nonlru(struct pag void __pagevec_lru_add(struct pagevec *pvec) { int i; - struct zone *zone = NULL; - - for (i = 0; i < pagevec_count(pvec); i++) { - struct page *page = pvec->pages[i]; - struct zone *pagezone = page_zone(page); + struct page *page; + struct zone *zone; - if (pagezone != zone) { - if (zone) - spin_unlock_irq(&zone->lru_lock); - zone = pagezone; - spin_lock_irq(&zone->lru_lock); - } + pagevec_for_each_page(pvec, i, page, zone) { if (TestSetPageLRU(page)) BUG(); ClearPageSkipped(page); add_page_to_inactive_list(zone, page); } - if (zone) - spin_unlock_irq(&zone->lru_lock); release_pages(pvec->pages, pvec->nr, pvec->cold); pagevec_reinit(pvec); } @@ -350,26 +363,16 @@ EXPORT_SYMBOL(__pagevec_lru_add); void __pagevec_lru_add_active(struct pagevec *pvec) { int i; - struct zone *zone = NULL; - - for (i = 0; i < pagevec_count(pvec); i++) { - struct page *page = pvec->pages[i]; - struct zone *pagezone = page_zone(page); + struct page *page; + struct zone *zone; - if (pagezone != zone) { - if (zone) - spin_unlock_irq(&zone->lru_lock); - zone = pagezone; - spin_lock_irq(&zone->lru_lock); - } + pagevec_for_each_page(pvec, i, page, zone) { if (TestSetPageLRU(page)) BUG(); if (TestSetPageActive(page)) BUG(); add_page_to_active_list(zone, page); } - if (zone) - spin_unlock_irq(&zone->lru_lock); release_pages(pvec->pages, pvec->nr, pvec->cold); pagevec_reinit(pvec); } _
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