- Replace @page with @mapping and @index,
which is a more usable interface.
- Add a new parameter @ra to rescue_pages(),
which enables detailed accounting for individual readahead methods.
- Scan all pages in the range, instead of bailing out on first uncached page.
- ClearPageReadahead() on each page.
It's harmful to have any lookahead marks when thrashing is pending.
- Add a call to rescue_pages() in thrashing_recovery_readahead().
Stress tested in qemu.
Signed-off-by: Fengguang Wu <[EMAIL PROTECTED]>
---
mm/readahead.c | 67 +++++++++++++++++++++++------------------------
1 file changed, 34 insertions(+), 33 deletions(-)
--- linux-2.6.21-rc3-mm2.orig/mm/readahead.c
+++ linux-2.6.21-rc3-mm2/mm/readahead.c
@@ -731,60 +731,60 @@ unsigned long max_sane_readahead(unsigne
/*
* Move pages in danger (of thrashing) to the head of inactive_list.
* Not expected to happen frequently.
- *
- * @page will be skipped: it's grabbed and won't die away.
- * The following @nr_pages-1 pages will be protected.
*/
-static unsigned long rescue_pages(struct page *page, unsigned long nr_pages)
+static unsigned long rescue_pages(struct address_space *mapping,
+ struct file_ra_state *ra,
+ pgoff_t index, unsigned long nr_pages)
{
- int pgrescue = 0;
- pgoff_t index = page_index(page);
- struct address_space *mapping = page_mapping(page);
- struct page *grabbed_page = NULL;
+ struct page *grabbed_page;
+ struct page *page;
struct zone *zone;
+ int pgrescue = 0;
- dprintk("rescue_pages(ino=%lu, index=%lu nr=%lu)\n",
+ dprintk("rescue_pages(ino=%lu, index=%lu, nr=%lu)\n",
mapping->host->i_ino, index, nr_pages);
- for(;;) {
+ for(; nr_pages;) {
+ grabbed_page = page = find_get_page(mapping, index);
+ if (!page) {
+ index++;
+ nr_pages--;
+ continue;
+ }
+
zone = page_zone(page);
spin_lock_irq(&zone->lru_lock);
- if (!PageLRU(page))
- goto out_unlock;
+ if (!PageLRU(page)) {
+ index++;
+ nr_pages--;
+ goto next_unlock;
+ }
- while (page_mapping(page) == mapping &&
- page_index(page) == index) {
+ do {
struct page *the_page = page;
page = list_entry((page)->lru.prev, struct page, lru);
+ index++;
+ nr_pages--;
+ ClearPageReadahead(the_page);
if (!PageActive(the_page) &&
!PageLocked(the_page) &&
page_count(the_page) == 1) {
list_move(&the_page->lru, &zone->inactive_list);
pgrescue++;
}
- index++;
- if (!--nr_pages)
- goto out_unlock;
- }
+ } while (nr_pages &&
+ page_mapping(page) == mapping &&
+ page_index(page) == index);
+next_unlock:
spin_unlock_irq(&zone->lru_lock);
+ page_cache_release(grabbed_page);
cond_resched();
-
- if (grabbed_page)
- page_cache_release(grabbed_page);
- grabbed_page = page = find_get_page(mapping, index);
- if (!page)
- goto out;
}
-out_unlock:
- spin_unlock_irq(&zone->lru_lock);
-out:
- if (grabbed_page)
- page_cache_release(grabbed_page);
- ra_account(NULL, RA_EVENT_READAHEAD_RESCUE, pgrescue);
- return nr_pages;
+ ra_account(ra, RA_EVENT_READAHEAD_RESCUE, pgrescue);
+ return pgrescue;
}
/*
@@ -1131,7 +1131,7 @@ clock_based_readahead(struct address_spa
ra_size = ra_size * readahead_ratio / 100;
if (page && remain_space <= la_size) {
- rescue_pages(page, la_size);
+ rescue_pages(mapping, ra, offset, la_size);
goto cancel_lookahead;
}
@@ -1456,7 +1456,7 @@ has_history_pages:
la_size = start - offset;
if (page && ra_size < la_size) {
if (ra_size < offset)
- rescue_pages(page, la_size);
+ rescue_pages(mapping, ra, offset, la_size);
return -1;
}
@@ -1584,6 +1584,7 @@ thrashing_recovery_readahead(struct addr
* Further thrashings will bring us back to case (3) below.
*/
ra_size = ra->readahead_index - offset;
+ rescue_pages(mapping, ra, offset, ra_size);
} else {
/*
* 3) The new chunk is lost.
--
-
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