diff options
| -rw-r--r-- | Documentation/filesystems/proc.txt | 9 | ||||
| -rw-r--r-- | fs/proc/meminfo.c | 37 |
2 files changed, 46 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 22d89aa37218..8533f5f9bb2d 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -767,6 +767,7 @@ The "Locked" indicates whether the mapping is locked in memory or not. MemTotal: 16344972 kB MemFree: 13634064 kB +MemAvailable: 14836172 kB Buffers: 3656 kB Cached: 1195708 kB SwapCached: 0 kB @@ -799,6 +800,14 @@ AnonHugePages: 49152 kB MemTotal: Total usable ram (i.e. physical ram minus a few reserved bits and the kernel binary code) MemFree: The sum of LowFree+HighFree +MemAvailable: An estimate of how much memory is available for starting new + applications, without swapping. Calculated from MemFree, + SReclaimable, the size of the file LRU lists, and the low + watermarks in each zone. + The estimate takes into account that the system needs some + page cache to function well, and that not all reclaimable + slab will be reclaimable, due to items being in use. The + impact of those factors will vary from system to system. Buffers: Relatively temporary storage for raw disk blocks shouldn't get tremendously large (20MB or so) Cached: in-memory cache for files read from the disk (the diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c index a77d2b299199..24270eceddbf 100644 --- a/fs/proc/meminfo.c +++ b/fs/proc/meminfo.c @@ -26,7 +26,11 @@ static int meminfo_proc_show(struct seq_file *m, void *v) unsigned long committed; struct vmalloc_info vmi; long cached; + long available; + unsigned long pagecache; + unsigned long wmark_low = 0; unsigned long pages[NR_LRU_LISTS]; + struct zone *zone; int lru; /* @@ -47,12 +51,44 @@ 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. + * + * Free memory cannot be taken below the low watermark, before the + * system starts swapping. + */ + available = i.freeram - wmark_low; + + /* + * 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 swap 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; + /* * Tagged format, for easy grepping and expansion. */ seq_printf(m, "MemTotal: %8lu kB\n" "MemFree: %8lu kB\n" + "MemAvailable: %8lu kB\n" "Buffers: %8lu kB\n" "Cached: %8lu kB\n" "SwapCached: %8lu kB\n" @@ -105,6 +141,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v) , K(i.totalram), K(i.freeram), + K(available), K(i.bufferram), K(cached), K(total_swapcache_pages()), |