From: Kirill A. Shutemov Date: Wed, 10 Mar 2010 23:22:24 +0000 (-0800) Subject: memcg: implement memory thresholds X-Git-Tag: Ubuntu-5.2.0-15.16~25762 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=2e72b6347c9459e6cff5634ddc815485bae6985f;p=mirror_ubuntu-eoan-kernel.git memcg: implement memory thresholds It allows to register multiple memory and memsw thresholds and gets notifications when it crosses. To register a threshold application need: - create an eventfd; - open memory.usage_in_bytes or memory.memsw.usage_in_bytes; - write string like " " to cgroup.event_control. Application will be notified through eventfd when memory usage crosses threshold in any direction. It's applicable for root and non-root cgroup. It uses stats to track memory usage, simmilar to soft limits. It checks if we need to send event to userspace on every 100 page in/out. I guess it's good compromise between performance and accuracy of thresholds. [akpm@linux-foundation.org: coding-style fixes] [nishimura@mxp.nes.nec.co.jp: fix documentation merge issue] Signed-off-by: Kirill A. Shutemov Cc: Li Zefan Cc: KAMEZAWA Hiroyuki Cc: Balbir Singh Cc: Pavel Emelyanov Cc: Dan Malek Cc: Vladislav Buzov Cc: Daisuke Nishimura Cc: Alexander Shishkin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 1f59a1a38bd9..268ab08222dd 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -468,7 +468,24 @@ Note: More type of pages(e.g. file cache, shmem,) will be supported by other - All of moving charge operations are done under cgroup_mutex. It's not good behavior to hold the mutex too long, so we may need some trick. -9. TODO +9. Memory thresholds + +Memory controler implements memory thresholds using cgroups notification +API (see cgroups.txt). It allows to register multiple memory and memsw +thresholds and gets notifications when it crosses. + +To register a threshold application need: + - create an eventfd using eventfd(2); + - open memory.usage_in_bytes or memory.memsw.usage_in_bytes; + - write string like " " to + cgroup.event_control. + +Application will be notified through eventfd when memory usage crosses +threshold in any direction. + +It's applicable for root and non-root cgroup. + +10. TODO 1. Add support for accounting huge pages (as a separate controller) 2. Make per-cgroup scanner reclaim not-shared pages first diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5a41d93c7077..649df435b8e2 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6,6 +6,10 @@ * Copyright 2007 OpenVZ SWsoft Inc * Author: Pavel Emelianov * + * Memory thresholds + * Copyright (C) 2009 Nokia Corporation + * Author: Kirill A. Shutemov + * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or @@ -35,6 +39,8 @@ #include #include #include +#include +#include #include #include #include @@ -58,6 +64,7 @@ static int really_do_swap_account __initdata = 1; /* for remember boot option*/ #endif #define SOFTLIMIT_EVENTS_THRESH (1000) +#define THRESHOLDS_EVENTS_THRESH (100) /* * Statistics for memory cgroup. @@ -74,6 +81,8 @@ enum mem_cgroup_stat_index { MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */ MEM_CGROUP_STAT_SOFTLIMIT, /* decrements on each page in/out. used by soft limit implementation */ + MEM_CGROUP_STAT_THRESHOLDS, /* decrements on each page in/out. + used by threshold implementation */ MEM_CGROUP_STAT_NSTATS, }; @@ -177,6 +186,23 @@ struct mem_cgroup_tree { static struct mem_cgroup_tree soft_limit_tree __read_mostly; +struct mem_cgroup_threshold { + struct eventfd_ctx *eventfd; + u64 threshold; +}; + +struct mem_cgroup_threshold_ary { + /* An array index points to threshold just below usage. */ + atomic_t current_threshold; + /* Size of entries[] */ + unsigned int size; + /* Array of thresholds */ + struct mem_cgroup_threshold entries[0]; +}; + +static bool mem_cgroup_threshold_check(struct mem_cgroup *mem); +static void mem_cgroup_threshold(struct mem_cgroup *mem); + /* * The memory controller data structure. The memory controller controls both * page cache and RSS per cgroup. We would eventually like to provide @@ -228,6 +254,15 @@ struct mem_cgroup { /* set when res.limit == memsw.limit */ bool memsw_is_minimum; + /* protect arrays of thresholds */ + struct mutex thresholds_lock; + + /* thresholds for memory usage. RCU-protected */ + struct mem_cgroup_threshold_ary *thresholds; + + /* thresholds for mem+swap usage. RCU-protected */ + struct mem_cgroup_threshold_ary *memsw_thresholds; + /* * Should we move charges of a task when a task is moved into this * mem_cgroup ? And what type of charges should we move ? @@ -549,6 +584,8 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_PGPGOUT_COUNT, 1); __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_SOFTLIMIT, -1); + __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_THRESHOLDS, -1); + put_cpu(); } @@ -1576,6 +1613,8 @@ charged: if (page && mem_cgroup_soft_limit_check(mem)) mem_cgroup_update_tree(mem, page); done: + if (mem_cgroup_threshold_check(mem)) + mem_cgroup_threshold(mem); return 0; nomem: css_put(&mem->css); @@ -2148,6 +2187,8 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) if (mem_cgroup_soft_limit_check(mem)) mem_cgroup_update_tree(mem, page); + if (mem_cgroup_threshold_check(mem)) + mem_cgroup_threshold(mem); /* at swapout, this memcg will be accessed to record to swap */ if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT) css_put(&mem->css); @@ -3232,12 +3273,277 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft, return 0; } +static bool mem_cgroup_threshold_check(struct mem_cgroup *mem) +{ + bool ret = false; + int cpu; + s64 val; + struct mem_cgroup_stat_cpu *cpustat; + + cpu = get_cpu(); + cpustat = &mem->stat.cpustat[cpu]; + val = __mem_cgroup_stat_read_local(cpustat, MEM_CGROUP_STAT_THRESHOLDS); + if (unlikely(val < 0)) { + __mem_cgroup_stat_set_safe(cpustat, MEM_CGROUP_STAT_THRESHOLDS, + THRESHOLDS_EVENTS_THRESH); + ret = true; + } + put_cpu(); + return ret; +} + +static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) +{ + struct mem_cgroup_threshold_ary *t; + u64 usage; + int i; + + rcu_read_lock(); + if (!swap) + t = rcu_dereference(memcg->thresholds); + else + t = rcu_dereference(memcg->memsw_thresholds); + + if (!t) + goto unlock; + + usage = mem_cgroup_usage(memcg, swap); + + /* + * current_threshold points to threshold just below usage. + * If it's not true, a threshold was crossed after last + * call of __mem_cgroup_threshold(). + */ + i = atomic_read(&t->current_threshold); + + /* + * Iterate backward over array of thresholds starting from + * current_threshold and check if a threshold is crossed. + * If none of thresholds below usage is crossed, we read + * only one element of the array here. + */ + for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--) + eventfd_signal(t->entries[i].eventfd, 1); + + /* i = current_threshold + 1 */ + i++; + + /* + * Iterate forward over array of thresholds starting from + * current_threshold+1 and check if a threshold is crossed. + * If none of thresholds above usage is crossed, we read + * only one element of the array here. + */ + for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++) + eventfd_signal(t->entries[i].eventfd, 1); + + /* Update current_threshold */ + atomic_set(&t->current_threshold, i - 1); +unlock: + rcu_read_unlock(); +} + +static void mem_cgroup_threshold(struct mem_cgroup *memcg) +{ + __mem_cgroup_threshold(memcg, false); + if (do_swap_account) + __mem_cgroup_threshold(memcg, true); +} + +static int compare_thresholds(const void *a, const void *b) +{ + const struct mem_cgroup_threshold *_a = a; + const struct mem_cgroup_threshold *_b = b; + + return _a->threshold - _b->threshold; +} + +static int mem_cgroup_register_event(struct cgroup *cgrp, struct cftype *cft, + struct eventfd_ctx *eventfd, const char *args) +{ + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); + struct mem_cgroup_threshold_ary *thresholds, *thresholds_new; + int type = MEMFILE_TYPE(cft->private); + u64 threshold, usage; + int size; + int i, ret; + + ret = res_counter_memparse_write_strategy(args, &threshold); + if (ret) + return ret; + + mutex_lock(&memcg->thresholds_lock); + if (type == _MEM) + thresholds = memcg->thresholds; + else if (type == _MEMSWAP) + thresholds = memcg->memsw_thresholds; + else + BUG(); + + usage = mem_cgroup_usage(memcg, type == _MEMSWAP); + + /* Check if a threshold crossed before adding a new one */ + if (thresholds) + __mem_cgroup_threshold(memcg, type == _MEMSWAP); + + if (thresholds) + size = thresholds->size + 1; + else + size = 1; + + /* Allocate memory for new array of thresholds */ + thresholds_new = kmalloc(sizeof(*thresholds_new) + + size * sizeof(struct mem_cgroup_threshold), + GFP_KERNEL); + if (!thresholds_new) { + ret = -ENOMEM; + goto unlock; + } + thresholds_new->size = size; + + /* Copy thresholds (if any) to new array */ + if (thresholds) + memcpy(thresholds_new->entries, thresholds->entries, + thresholds->size * + sizeof(struct mem_cgroup_threshold)); + /* Add new threshold */ + thresholds_new->entries[size - 1].eventfd = eventfd; + thresholds_new->entries[size - 1].threshold = threshold; + + /* Sort thresholds. Registering of new threshold isn't time-critical */ + sort(thresholds_new->entries, size, + sizeof(struct mem_cgroup_threshold), + compare_thresholds, NULL); + + /* Find current threshold */ + atomic_set(&thresholds_new->current_threshold, -1); + for (i = 0; i < size; i++) { + if (thresholds_new->entries[i].threshold < usage) { + /* + * thresholds_new->current_threshold will not be used + * until rcu_assign_pointer(), so it's safe to increment + * it here. + */ + atomic_inc(&thresholds_new->current_threshold); + } + } + + /* + * We need to increment refcnt to be sure that all thresholds + * will be unregistered before calling __mem_cgroup_free() + */ + mem_cgroup_get(memcg); + + if (type == _MEM) + rcu_assign_pointer(memcg->thresholds, thresholds_new); + else + rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new); + + /* To be sure that nobody uses thresholds before freeing it */ + synchronize_rcu(); + + kfree(thresholds); +unlock: + mutex_unlock(&memcg->thresholds_lock); + + return ret; +} + +static int mem_cgroup_unregister_event(struct cgroup *cgrp, struct cftype *cft, + struct eventfd_ctx *eventfd) +{ + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); + struct mem_cgroup_threshold_ary *thresholds, *thresholds_new; + int type = MEMFILE_TYPE(cft->private); + u64 usage; + int size = 0; + int i, j, ret; + + mutex_lock(&memcg->thresholds_lock); + if (type == _MEM) + thresholds = memcg->thresholds; + else if (type == _MEMSWAP) + thresholds = memcg->memsw_thresholds; + else + BUG(); + + /* + * Something went wrong if we trying to unregister a threshold + * if we don't have thresholds + */ + BUG_ON(!thresholds); + + usage = mem_cgroup_usage(memcg, type == _MEMSWAP); + + /* Check if a threshold crossed before removing */ + __mem_cgroup_threshold(memcg, type == _MEMSWAP); + + /* Calculate new number of threshold */ + for (i = 0; i < thresholds->size; i++) { + if (thresholds->entries[i].eventfd != eventfd) + size++; + } + + /* Set thresholds array to NULL if we don't have thresholds */ + if (!size) { + thresholds_new = NULL; + goto assign; + } + + /* Allocate memory for new array of thresholds */ + thresholds_new = kmalloc(sizeof(*thresholds_new) + + size * sizeof(struct mem_cgroup_threshold), + GFP_KERNEL); + if (!thresholds_new) { + ret = -ENOMEM; + goto unlock; + } + thresholds_new->size = size; + + /* Copy thresholds and find current threshold */ + atomic_set(&thresholds_new->current_threshold, -1); + for (i = 0, j = 0; i < thresholds->size; i++) { + if (thresholds->entries[i].eventfd == eventfd) + continue; + + thresholds_new->entries[j] = thresholds->entries[i]; + if (thresholds_new->entries[j].threshold < usage) { + /* + * thresholds_new->current_threshold will not be used + * until rcu_assign_pointer(), so it's safe to increment + * it here. + */ + atomic_inc(&thresholds_new->current_threshold); + } + j++; + } + +assign: + if (type == _MEM) + rcu_assign_pointer(memcg->thresholds, thresholds_new); + else + rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new); + + /* To be sure that nobody uses thresholds before freeing it */ + synchronize_rcu(); + + for (i = 0; i < thresholds->size - size; i++) + mem_cgroup_put(memcg); + + kfree(thresholds); +unlock: + mutex_unlock(&memcg->thresholds_lock); + + return ret; +} static struct cftype mem_cgroup_files[] = { { .name = "usage_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_USAGE), .read_u64 = mem_cgroup_read, + .register_event = mem_cgroup_register_event, + .unregister_event = mem_cgroup_unregister_event, }, { .name = "max_usage_in_bytes", @@ -3294,6 +3600,8 @@ static struct cftype memsw_cgroup_files[] = { .name = "memsw.usage_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), .read_u64 = mem_cgroup_read, + .register_event = mem_cgroup_register_event, + .unregister_event = mem_cgroup_unregister_event, }, { .name = "memsw.max_usage_in_bytes", @@ -3538,6 +3846,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont) mem->swappiness = get_swappiness(parent); atomic_set(&mem->refcnt, 1); mem->move_charge_at_immigrate = 0; + mutex_init(&mem->thresholds_lock); return &mem->css; free_out: __mem_cgroup_free(mem);