From: Igor Redko <redkoi@xxxxxxxxxxxxx>
Factor out calculation of the available memory counter into a separate
exportable function, in order to be able to use it in other parts of
the kernel.
In particular, it appears a relevant metric to report to the
hypervisor via virtio-balloon statistics interface (in a followup
patch).
Signed-off-by: Igor Redko <redkoi@xxxxxxxxxxxxx>
Reviewed-by: Roman Kagan <rkagan@xxxxxxxxxxxxx>
Signed-off-by: Denis V. Lunev <den@xxxxxxxxxx>
CC: Michael S. Tsirkin <mst@xxxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/meminfo.c | 31 +------------------------------
include/linux/mm.h | 1 +
mm/page_alloc.c | 43 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 45 insertions(+), 30 deletions(-)
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index df4661a..8372046 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -29,10 +29,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
unsigned long committed;
long cached;
long available;
- unsigned long pagecache;
- unsigned long wmark_low = 0;
unsigned long pages[NR_LRU_LISTS];
- struct zone *zone;
int lru;
/*
@@ -51,33 +48,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
pages[lru] = global_page_state(NR_LRU_BASE + lru);
- for_each_zone(zone)
- wmark_low += zone->watermark[WMARK_LOW];
-
- /*
- * Estimate the amount of memory available for userspace allocations,
- * without causing swapping.
- */
- available = i.freeram - totalreserve_pages;
-
- /*
- * 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.
- */
- pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
- pagecache -= min(pagecache / 2, wmark_low);
- available += pagecache;
-
- /*
- * Part of the reclaimable slab consists of items that are in use,
- * and cannot be freed. Cap this estimate at the low watermark.
- */
- available += global_page_state(NR_SLAB_RECLAIMABLE) -
- min(global_page_state(NR_SLAB_RECLAIMABLE) / 2, wmark_low);
-
- if (available < 0)
- available = 0;
+ available = si_mem_available();
/*
* Tagged format, for easy grepping and expansion.
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 516e149..a8c4144 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1862,6 +1862,7 @@ extern int __meminit init_per_zone_wmark_min(void);
extern void mem_init(void);
extern void __init mmap_init(void);
extern void show_mem(unsigned int flags);
+extern long si_mem_available(void);
extern void si_meminfo(struct sysinfo * val);
extern void si_meminfo_node(struct sysinfo *val, int nid);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 838ca8bb..dae813c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3603,6 +3603,49 @@ static inline void show_node(struct zone *zone)
printk("Node %d ", zone_to_nid(zone));
}
+long si_mem_available(void)
+{
+ long available;
+ unsigned long pagecache;
+ unsigned long wmark_low = 0;
+ unsigned long pages[NR_LRU_LISTS];
+ struct zone *zone;
+ int lru;
+
+ for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
+ pages[lru] = global_page_state(NR_LRU_BASE + lru);
+
+ for_each_zone(zone)
+ wmark_low += zone->watermark[WMARK_LOW];
+
+ /*
+ * Estimate the amount of memory available for userspace allocations,
+ * without causing swapping.
+ */
+ available = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
+
+ /*
+ * 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.
+ */
+ pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
+ pagecache -= min(pagecache / 2, wmark_low);
+ available += pagecache;
+
+ /*
+ * Part of the reclaimable slab consists of items that are in use,
+ * and cannot be freed. Cap this estimate at the low watermark.
+ */
+ available += global_page_state(NR_SLAB_RECLAIMABLE) -
+ min(global_page_state(NR_SLAB_RECLAIMABLE) / 2, wmark_low);
+
+ if (available < 0)
+ available = 0;
+ return available;
+}
+EXPORT_SYMBOL_GPL(si_mem_available);
+
void si_meminfo(struct sysinfo *val)
{
val->totalram = totalram_pages;
--
2.5.0
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