From 5660048ccac8735d9bc0a46325a02e6a6518b5b2 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Thu, 12 Jan 2012 17:17:59 -0800 Subject: [PATCH] mm: move memcg hierarchy reclaim to generic reclaim code Memory cgroup limit reclaim and traditional global pressure reclaim will soon share the same code to reclaim from a hierarchical tree of memory cgroups. In preparation of this, move the two right next to each other in shrink_zone(). The mem_cgroup_hierarchical_reclaim() polymath is split into a soft limit reclaim function, which still does hierarchy walking on its own, and a limit (shrinking) reclaim function, which relies on generic reclaim code to walk the hierarchy. Signed-off-by: Johannes Weiner Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: Michal Hocko Reviewed-by: Kirill A. Shutemov Cc: Daisuke Nishimura Cc: Balbir Singh Cc: Ying Han Cc: Greg Thelen Cc: Michel Lespinasse Cc: Rik van Riel Cc: Minchan Kim Cc: Christoph Hellwig Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memcontrol.h | 24 +++++++ mm/memcontrol.c | 169 +++++++++++++++++++++++---------------------- mm/vmscan.c | 43 ++++++++++-- 3 files changed, 148 insertions(+), 88 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 3558a5e..3b99dce 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -40,6 +40,12 @@ extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, struct mem_cgroup *mem_cont, int active, int file); +struct mem_cgroup_reclaim_cookie { + struct zone *zone; + int priority; + unsigned int generation; +}; + #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* * All "charge" functions with gfp_mask should use GFP_KERNEL or @@ -106,6 +112,11 @@ mem_cgroup_prepare_migration(struct page *page, extern void mem_cgroup_end_migration(struct mem_cgroup *memcg, struct page *oldpage, struct page *newpage, bool migration_ok); +struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *, + struct mem_cgroup *, + struct mem_cgroup_reclaim_cookie *); +void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *); + /* * For memory reclaim. */ @@ -281,6 +292,19 @@ static inline void mem_cgroup_end_migration(struct mem_cgroup *memcg, { } +static inline struct mem_cgroup * +mem_cgroup_iter(struct mem_cgroup *root, + struct mem_cgroup *prev, + struct mem_cgroup_reclaim_cookie *reclaim) +{ + return NULL; +} + +static inline void mem_cgroup_iter_break(struct mem_cgroup *root, + struct mem_cgroup *prev) +{ +} + static inline int mem_cgroup_get_reclaim_priority(struct mem_cgroup *memcg) { return 0; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index bec451d..750ed14 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -370,8 +370,6 @@ enum charge_type { #define MEM_CGROUP_RECLAIM_NOSWAP (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT) #define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1 #define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT) -#define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2 -#define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT) static void mem_cgroup_get(struct mem_cgroup *memcg); static void mem_cgroup_put(struct mem_cgroup *memcg); @@ -857,20 +855,33 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) return memcg; } -struct mem_cgroup_reclaim_cookie { - struct zone *zone; - int priority; - unsigned int generation; -}; - -static struct mem_cgroup * -mem_cgroup_iter(struct mem_cgroup *root, - struct mem_cgroup *prev, - struct mem_cgroup_reclaim_cookie *reclaim) +/** + * mem_cgroup_iter - iterate over memory cgroup hierarchy + * @root: hierarchy root + * @prev: previously returned memcg, NULL on first invocation + * @reclaim: cookie for shared reclaim walks, NULL for full walks + * + * Returns references to children of the hierarchy below @root, or + * @root itself, or %NULL after a full round-trip. + * + * Caller must pass the return value in @prev on subsequent + * invocations for reference counting, or use mem_cgroup_iter_break() + * to cancel a hierarchy walk before the round-trip is complete. + * + * Reclaimers can specify a zone and a priority level in @reclaim to + * divide up the memcgs in the hierarchy among all concurrent + * reclaimers operating on the same zone and priority. + */ +struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, + struct mem_cgroup *prev, + struct mem_cgroup_reclaim_cookie *reclaim) { struct mem_cgroup *memcg = NULL; int id = 0; + if (mem_cgroup_disabled()) + return NULL; + if (!root) root = root_mem_cgroup; @@ -926,8 +937,13 @@ mem_cgroup_iter(struct mem_cgroup *root, return memcg; } -static void mem_cgroup_iter_break(struct mem_cgroup *root, - struct mem_cgroup *prev) +/** + * mem_cgroup_iter_break - abort a hierarchy walk prematurely + * @root: hierarchy root + * @prev: last visited hierarchy member as returned by mem_cgroup_iter() + */ +void mem_cgroup_iter_break(struct mem_cgroup *root, + struct mem_cgroup *prev) { if (!root) root = root_mem_cgroup; @@ -1555,6 +1571,42 @@ u64 mem_cgroup_get_limit(struct mem_cgroup *memcg) return min(limit, memsw); } +static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg, + gfp_t gfp_mask, + unsigned long flags) +{ + unsigned long total = 0; + bool noswap = false; + int loop; + + if (flags & MEM_CGROUP_RECLAIM_NOSWAP) + noswap = true; + if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum) + noswap = true; + + for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) { + if (loop) + drain_all_stock_async(memcg); + total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap); + /* + * Allow limit shrinkers, which are triggered directly + * by userspace, to catch signals and stop reclaim + * after minimal progress, regardless of the margin. + */ + if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK)) + break; + if (mem_cgroup_margin(memcg)) + break; + /* + * If nothing was reclaimed after two attempts, there + * may be no reclaimable pages in this hierarchy. + */ + if (loop && !total) + break; + } + return total; +} + /** * test_mem_cgroup_node_reclaimable * @mem: the target memcg @@ -1692,30 +1744,14 @@ bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) } #endif -/* - * Scan the hierarchy if needed to reclaim memory. We remember the last child - * we reclaimed from, so that we don't end up penalizing one child extensively - * based on its position in the children list. - * - * root_memcg is the original ancestor that we've been reclaim from. - * - * We give up and return to the caller when we visit root_memcg twice. - * (other groups can be removed while we're walking....) - * - * If shrink==true, for avoiding to free too much, this returns immedieately. - */ -static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_memcg, - struct zone *zone, - gfp_t gfp_mask, - unsigned long reclaim_options, - unsigned long *total_scanned) +static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, + struct zone *zone, + gfp_t gfp_mask, + unsigned long *total_scanned) { struct mem_cgroup *victim = NULL; - int ret, total = 0; + int total = 0; int loop = 0; - bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP; - bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK; - bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT; unsigned long excess; unsigned long nr_scanned; struct mem_cgroup_reclaim_cookie reclaim = { @@ -1725,29 +1761,17 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_memcg, excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT; - /* If memsw_is_minimum==1, swap-out is of-no-use. */ - if (!check_soft && !shrink && root_memcg->memsw_is_minimum) - noswap = true; - while (1) { victim = mem_cgroup_iter(root_memcg, victim, &reclaim); if (!victim) { loop++; - /* - * We are not draining per cpu cached charges during - * soft limit reclaim because global reclaim doesn't - * care about charges. It tries to free some memory and - * charges will not give any. - */ - if (!check_soft && loop >= 1) - drain_all_stock_async(root_memcg); if (loop >= 2) { /* * If we have not been able to reclaim * anything, it might because there are * no reclaimable pages under this hierarchy */ - if (!check_soft || !total) + if (!total) break; /* * We want to do more targeted reclaim. @@ -1761,30 +1785,12 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_memcg, } continue; } - if (!mem_cgroup_reclaimable(victim, noswap)) { - /* this cgroup's local usage == 0 */ + if (!mem_cgroup_reclaimable(victim, false)) continue; - } - /* we use swappiness of local cgroup */ - if (check_soft) { - ret = mem_cgroup_shrink_node_zone(victim, gfp_mask, - noswap, zone, &nr_scanned); - *total_scanned += nr_scanned; - } else - ret = try_to_free_mem_cgroup_pages(victim, gfp_mask, - noswap); - total += ret; - /* - * At shrinking usage, we can't check we should stop here or - * reclaim more. It's depends on callers. last_scanned_child - * will work enough for keeping fairness under tree. - */ - if (shrink) - break; - if (check_soft) { - if (!res_counter_soft_limit_excess(&root_memcg->res)) - break; - } else if (mem_cgroup_margin(root_memcg)) + total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false, + zone, &nr_scanned); + *total_scanned += nr_scanned; + if (!res_counter_soft_limit_excess(&root_memcg->res)) break; } mem_cgroup_iter_break(root_memcg, victim); @@ -2281,8 +2287,7 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, if (!(gfp_mask & __GFP_WAIT)) return CHARGE_WOULDBLOCK; - ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL, - gfp_mask, flags, NULL); + ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); if (mem_cgroup_margin(mem_over_limit) >= nr_pages) return CHARGE_RETRY; /* @@ -3559,9 +3564,8 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, if (!ret) break; - mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL, - MEM_CGROUP_RECLAIM_SHRINK, - NULL); + mem_cgroup_reclaim(memcg, GFP_KERNEL, + MEM_CGROUP_RECLAIM_SHRINK); curusage = res_counter_read_u64(&memcg->res, RES_USAGE); /* Usage is reduced ? */ if (curusage >= oldusage) @@ -3619,10 +3623,9 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg, if (!ret) break; - mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL, - MEM_CGROUP_RECLAIM_NOSWAP | - MEM_CGROUP_RECLAIM_SHRINK, - NULL); + mem_cgroup_reclaim(memcg, GFP_KERNEL, + MEM_CGROUP_RECLAIM_NOSWAP | + MEM_CGROUP_RECLAIM_SHRINK); curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE); /* Usage is reduced ? */ if (curusage >= oldusage) @@ -3665,10 +3668,8 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, break; nr_scanned = 0; - reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone, - gfp_mask, - MEM_CGROUP_RECLAIM_SOFT, - &nr_scanned); + reclaimed = mem_cgroup_soft_reclaim(mz->mem, zone, + gfp_mask, &nr_scanned); nr_reclaimed += reclaimed; *total_scanned += nr_scanned; spin_lock(&mctz->lock); diff --git a/mm/vmscan.c b/mm/vmscan.c index e0627d0..136c7eb 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2104,12 +2104,43 @@ restart: static void shrink_zone(int priority, struct zone *zone, struct scan_control *sc) { - struct mem_cgroup_zone mz = { - .mem_cgroup = sc->target_mem_cgroup, + struct mem_cgroup *root = sc->target_mem_cgroup; + struct mem_cgroup_reclaim_cookie reclaim = { .zone = zone, + .priority = priority, }; + struct mem_cgroup *memcg; + + if (global_reclaim(sc)) { + struct mem_cgroup_zone mz = { + .mem_cgroup = NULL, + .zone = zone, + }; + + shrink_mem_cgroup_zone(priority, &mz, sc); + return; + } + + memcg = mem_cgroup_iter(root, NULL, &reclaim); + do { + struct mem_cgroup_zone mz = { + .mem_cgroup = memcg, + .zone = zone, + }; - shrink_mem_cgroup_zone(priority, &mz, sc); + shrink_mem_cgroup_zone(priority, &mz, sc); + /* + * Limit reclaim has historically picked one memcg and + * scanned it with decreasing priority levels until + * nr_to_reclaim had been reclaimed. This priority + * cycle is thus over after a single memcg. + */ + if (!global_reclaim(sc)) { + mem_cgroup_iter_break(root, memcg); + break; + } + memcg = mem_cgroup_iter(root, memcg, &reclaim); + } while (memcg); } /* @@ -2374,6 +2405,10 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, .order = 0, .target_mem_cgroup = mem, }; + struct mem_cgroup_zone mz = { + .mem_cgroup = mem, + .zone = zone, + }; sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); @@ -2389,7 +2424,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, * will pick up pages from other mem cgroup's as well. We hack * the priority and make it zero. */ - shrink_zone(0, zone, &sc); + shrink_mem_cgroup_zone(0, &mz, &sc); trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); -- 2.7.4