When si_mem_available() calculates 'available', it takes SWAP
into account. But if CONFIG_SWAP is N or SWAP is off(some embedded system
would like to do that), there is no need to consider it.
Signed-off-by: Yang Yang <yang.yang29@xxxxxxxxxx>
---
mm/page_alloc.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6847177..10e186b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4700,6 +4700,7 @@ static inline void show_node(struct zone *zone)
long si_mem_available(void)
{
+ struct sysinfo i;
long available;
unsigned long pagecache;
unsigned long wmark_low = 0;
@@ -4708,6 +4709,7 @@ long si_mem_available(void)
struct zone *zone;
int lru;
+ si_swapinfo(&i);
for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
pages[lru] = global_node_page_state(NR_LRU_BASE + lru);
@@ -4724,9 +4726,13 @@ long si_mem_available(void)
* Not all the page cache can be freed, otherwise the system will
* start swapping. Assume at least half of the page cache, or the
* low watermark worth of cache, needs to stay.
+ * But if CONFIG_SWAP is N or SWAP is off, do not consider it.
*/
pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
- pagecache -= min(pagecache / 2, wmark_low);
+#ifdef CONFIG_SWAP
+ if (i.totalswap > 0)
+ pagecache -= min(pagecache / 2, wmark_low);
+#endif
available += pagecache;
/*
--
2.15.2
