3.16.72-rc1 review patch. If anyone has any objections, please let me know.
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From: Igor Redko redkoi@virtuozzo.com
commit d02bd27bd33dd7e8d22594cd568b81be0cb584cd upstream.
Add a new field, VIRTIO_BALLOON_S_AVAIL, to virtio_balloon memory statistics protocol, corresponding to 'Available' in /proc/meminfo.
It indicates to the hypervisor how big the balloon can be inflated without pushing the guest system to swap. This metric would be very useful in VM orchestration software to improve memory management of different VMs under overcommit.
This patch (of 2):
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@virtuozzo.com Signed-off-by: Denis V. Lunev den@openvz.org Reviewed-by: Roman Kagan rkagan@virtuozzo.com Cc: Michael S. Tsirkin mst@redhat.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org [bwh: Backported to 3.16 as dependency of commit a1078e821b60 "xen: let alloc_xenballooned_pages() fail if not enough memory free"] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/proc/meminfo.c | 31 +------------------------------ include/linux/mm.h | 1 + mm/page_alloc.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 45 insertions(+), 30 deletions(-)
--- a/fs/proc/meminfo.c +++ b/fs/proc/meminfo.c @@ -27,10 +27,7 @@ static int meminfo_proc_show(struct seq_ 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;
/* @@ -51,33 +48,7 @@ static int meminfo_proc_show(struct seq_ 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. --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1699,6 +1699,7 @@ extern int __meminit init_per_zone_wmark 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);
--- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3072,6 +3072,49 @@ static inline void show_node(struct 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;