Use the new read_page_state() in page-writeback.c to avoid large on-stack
structures.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/mm/page-writeback.c | 68 +++++++++++++++++++++++++++-----------------
1 files changed, 42 insertions(+), 26 deletions(-)
diff -puN mm/page-writeback.c~page-writeback-use-read_page_state mm/page-writeback.c
--- 25/mm/page-writeback.c~page-writeback-use-read_page_state Tue Jun 8 16:18:04 2004
+++ 25-akpm/mm/page-writeback.c Tue Jun 8 16:18:04 2004
@@ -99,6 +99,22 @@ EXPORT_SYMBOL(laptop_mode);
static void background_writeout(unsigned long _min_pages);
+struct writeback_state
+{
+ unsigned long nr_dirty;
+ unsigned long nr_unstable;
+ unsigned long nr_mapped;
+ unsigned long nr_writeback;
+};
+
+static void get_writeback_state(struct writeback_state *wbs)
+{
+ wbs->nr_dirty = read_page_state(nr_dirty);
+ wbs->nr_unstable = read_page_state(nr_unstable);
+ wbs->nr_mapped = read_page_state(nr_mapped);
+ wbs->nr_writeback = read_page_state(nr_writeback);
+}
+
/*
* Work out the current dirty-memory clamping and background writeout
* thresholds.
@@ -117,7 +133,7 @@ static void background_writeout(unsigned
* clamping level.
*/
static void
-get_dirty_limits(struct page_state *ps, long *pbackground, long *pdirty)
+get_dirty_limits(struct writeback_state *wbs, long *pbackground, long *pdirty)
{
int background_ratio; /* Percentages */
int dirty_ratio;
@@ -126,9 +142,9 @@ get_dirty_limits(struct page_state *ps,
long dirty;
struct task_struct *tsk;
- get_page_state(ps);
+ get_writeback_state(wbs);
- unmapped_ratio = 100 - (ps->nr_mapped * 100) / total_pages;
+ unmapped_ratio = 100 - (wbs->nr_mapped * 100) / total_pages;
dirty_ratio = vm_dirty_ratio;
if (dirty_ratio > unmapped_ratio / 2)
@@ -161,7 +177,7 @@ get_dirty_limits(struct page_state *ps,
*/
static void balance_dirty_pages(struct address_space *mapping)
{
- struct page_state ps;
+ struct writeback_state wbs;
long nr_reclaimable;
long background_thresh;
long dirty_thresh;
@@ -178,9 +194,9 @@ static void balance_dirty_pages(struct a
.nr_to_write = write_chunk,
};
- get_dirty_limits(&ps, &background_thresh, &dirty_thresh);
- nr_reclaimable = ps.nr_dirty + ps.nr_unstable;
- if (nr_reclaimable + ps.nr_writeback <= dirty_thresh)
+ get_dirty_limits(&wbs, &background_thresh, &dirty_thresh);
+ nr_reclaimable = wbs.nr_dirty + wbs.nr_unstable;
+ if (nr_reclaimable + wbs.nr_writeback <= dirty_thresh)
break;
dirty_exceeded = 1;
@@ -193,10 +209,10 @@ static void balance_dirty_pages(struct a
*/
if (nr_reclaimable) {
writeback_inodes(&wbc);
- get_dirty_limits(&ps, &background_thresh,
+ get_dirty_limits(&wbs, &background_thresh,
&dirty_thresh);
- nr_reclaimable = ps.nr_dirty + ps.nr_unstable;
- if (nr_reclaimable + ps.nr_writeback <= dirty_thresh)
+ nr_reclaimable = wbs.nr_dirty + wbs.nr_unstable;
+ if (nr_reclaimable + wbs.nr_writeback <= dirty_thresh)
break;
pages_written += write_chunk - wbc.nr_to_write;
if (pages_written >= write_chunk)
@@ -205,7 +221,7 @@ static void balance_dirty_pages(struct a
blk_congestion_wait(WRITE, HZ/10);
}
- if (nr_reclaimable + ps.nr_writeback <= dirty_thresh)
+ if (nr_reclaimable + wbs.nr_writeback <= dirty_thresh)
dirty_exceeded = 0;
if (writeback_in_progress(bdi))
@@ -232,10 +248,10 @@ static void balance_dirty_pages(struct a
* which was newly dirtied. The function will periodically check the system's
* dirty state and will initiate writeback if needed.
*
- * On really big machines, get_page_state is expensive, so try to avoid calling
- * it too often (ratelimiting). But once we're over the dirty memory limit we
- * decrease the ratelimiting by a lot, to prevent individual processes from
- * overshooting the limit by (ratelimit_pages) each.
+ * On really big machines, get_writeback_state is expensive, so try to avoid
+ * calling it too often (ratelimiting). But once we're over the dirty memory
+ * limit we decrease the ratelimiting by a lot, to prevent individual processes
+ * from overshooting the limit by (ratelimit_pages) each.
*/
void balance_dirty_pages_ratelimited(struct address_space *mapping)
{
@@ -276,12 +292,12 @@ static void background_writeout(unsigned
};
for ( ; ; ) {
- struct page_state ps;
+ struct writeback_state wbs;
long background_thresh;
long dirty_thresh;
- get_dirty_limits(&ps, &background_thresh, &dirty_thresh);
- if (ps.nr_dirty + ps.nr_unstable < background_thresh
+ get_dirty_limits(&wbs, &background_thresh, &dirty_thresh);
+ if (wbs.nr_dirty + wbs.nr_unstable < background_thresh
&& min_pages <= 0)
break;
wbc.encountered_congestion = 0;
@@ -306,10 +322,10 @@ static void background_writeout(unsigned
int wakeup_bdflush(long nr_pages)
{
if (nr_pages == 0) {
- struct page_state ps;
+ struct writeback_state wbs;
- get_page_state(&ps);
- nr_pages = ps.nr_dirty + ps.nr_unstable;
+ get_writeback_state(&wbs);
+ nr_pages = wbs.nr_dirty + wbs.nr_unstable;
}
return pdflush_operation(background_writeout, nr_pages);
}
@@ -343,7 +359,7 @@ static void wb_kupdate(unsigned long arg
unsigned long start_jif;
unsigned long next_jif;
long nr_to_write;
- struct page_state ps;
+ struct writeback_state wbs;
struct writeback_control wbc = {
.bdi = NULL,
.sync_mode = WB_SYNC_NONE,
@@ -355,11 +371,11 @@ static void wb_kupdate(unsigned long arg
sync_supers();
- get_page_state(&ps);
+ get_writeback_state(&wbs);
oldest_jif = jiffies - (dirty_expire_centisecs * HZ) / 100;
start_jif = jiffies;
next_jif = start_jif + (dirty_writeback_centisecs * HZ) / 100;
- nr_to_write = ps.nr_dirty + ps.nr_unstable +
+ nr_to_write = wbs.nr_dirty + wbs.nr_unstable +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
while (nr_to_write > 0) {
wbc.encountered_congestion = 0;
@@ -434,8 +450,8 @@ void laptop_sync_completion(void)
/*
* If ratelimit_pages is too high then we can get into dirty-data overload
* if a large number of processes all perform writes at the same time.
- * If it is too low then SMP machines will call the (expensive) get_page_state
- * too often.
+ * If it is too low then SMP machines will call the (expensive)
+ * get_writeback_state too often.
*
* Here we set ratelimit_pages to a level which ensures that when all CPUs are
* dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory
_