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memcg: clean up memory thresholds

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Introduce struct mem_cgroup_thresholds.  It helps to reduce number of
checks of thresholds type (memory or mem+swap).

[akpm@linux-foundation.org: repair comment]
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2010-05-26 14:42:47 -07:00 committed by Linus Torvalds
parent 907860ed38
commit 2c488db27b
1 changed files with 66 additions and 85 deletions
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151
mm/memcontrol.c
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@ -158,6 +158,18 @@ struct mem_cgroup_threshold_ary {
/* Array of thresholds */
struct mem_cgroup_threshold entries[0];
};
struct mem_cgroup_thresholds {
/* Primary thresholds array */
struct mem_cgroup_threshold_ary *primary;
/*
* Spare threshold array.
* This is needed to make mem_cgroup_unregister_event() "never fail".
* It must be able to store at least primary->size - 1 entries.
*/
struct mem_cgroup_threshold_ary *spare;
};
/* for OOM */
struct mem_cgroup_eventfd_list {
struct list_head list;
@ -224,20 +236,10 @@ struct mem_cgroup {
struct mutex thresholds_lock;
/* thresholds for memory usage. RCU-protected */
struct mem_cgroup_threshold_ary *thresholds;
/*
* Preallocated buffer to be used in mem_cgroup_unregister_event()
* to make it "never fail".
* It must be able to store at least thresholds->size - 1 entries.
*/
struct mem_cgroup_threshold_ary *__thresholds;
struct mem_cgroup_thresholds thresholds;
/* thresholds for mem+swap usage. RCU-protected */
struct mem_cgroup_threshold_ary *memsw_thresholds;
/* the same as __thresholds, but for memsw_thresholds */
struct mem_cgroup_threshold_ary *__memsw_thresholds;
struct mem_cgroup_thresholds memsw_thresholds;
/* For oom notifier event fd */
struct list_head oom_notify;
@ -3467,9 +3469,9 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
rcu_read_lock();
if (!swap)
t = rcu_dereference(memcg->thresholds);
t = rcu_dereference(memcg->thresholds.primary);
else
t = rcu_dereference(memcg->memsw_thresholds);
t = rcu_dereference(memcg->memsw_thresholds.primary);
if (!t)
goto unlock;
@ -3543,91 +3545,78 @@ static int mem_cgroup_usage_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;
struct mem_cgroup_thresholds *thresholds;
struct mem_cgroup_threshold_ary *new;
int type = MEMFILE_TYPE(cft->private);
u64 threshold, usage;
int size;
int i, ret;
int i, size, ret;
ret = res_counter_memparse_write_strategy(args, &threshold);
if (ret)
return ret;
mutex_lock(&memcg->thresholds_lock);
if (type == _MEM)
thresholds = memcg->thresholds;
thresholds = &memcg->thresholds;
else if (type == _MEMSWAP)
thresholds = memcg->memsw_thresholds;
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)
if (thresholds->primary)
__mem_cgroup_threshold(memcg, type == _MEMSWAP);
if (thresholds)
size = thresholds->size + 1;
else
size = 1;
size = thresholds->primary ? thresholds->primary->size + 1 : 1;
/* Allocate memory for new array of thresholds */
thresholds_new = kmalloc(sizeof(*thresholds_new) +
size * sizeof(struct mem_cgroup_threshold),
new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
GFP_KERNEL);
if (!thresholds_new) {
if (!new) {
ret = -ENOMEM;
goto unlock;
}
thresholds_new->size = size;
new->size = size;
/* Copy thresholds (if any) to new array */
if (thresholds)
memcpy(thresholds_new->entries, thresholds->entries,
thresholds->size *
if (thresholds->primary) {
memcpy(new->entries, thresholds->primary->entries, (size - 1) *
sizeof(struct mem_cgroup_threshold));
}
/* Add new threshold */
thresholds_new->entries[size - 1].eventfd = eventfd;
thresholds_new->entries[size - 1].threshold = threshold;
new->entries[size - 1].eventfd = eventfd;
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),
sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
compare_thresholds, NULL);
/* Find current threshold */
thresholds_new->current_threshold = -1;
new->current_threshold = -1;
for (i = 0; i < size; i++) {
if (thresholds_new->entries[i].threshold < usage) {
if (new->entries[i].threshold < usage) {
/*
* thresholds_new->current_threshold will not be used
* until rcu_assign_pointer(), so it's safe to increment
* new->current_threshold will not be used until
* rcu_assign_pointer(), so it's safe to increment
* it here.
*/
++thresholds_new->current_threshold;
++new->current_threshold;
}
}
if (type == _MEM)
rcu_assign_pointer(memcg->thresholds, thresholds_new);
else
rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new);
/* Free old spare buffer and save old primary buffer as spare */
kfree(thresholds->spare);
thresholds->spare = thresholds->primary;
rcu_assign_pointer(thresholds->primary, new);
/* To be sure that nobody uses thresholds */
synchronize_rcu();
/*
* Free old preallocated buffer and use thresholds as new
* preallocated buffer.
*/
if (type == _MEM) {
kfree(memcg->__thresholds);
memcg->__thresholds = thresholds;
} else {
kfree(memcg->__memsw_thresholds);
memcg->__memsw_thresholds = thresholds;
}
unlock:
mutex_unlock(&memcg->thresholds_lock);
@ -3638,17 +3627,17 @@ static void mem_cgroup_usage_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;
struct mem_cgroup_thresholds *thresholds;
struct mem_cgroup_threshold_ary *new;
int type = MEMFILE_TYPE(cft->private);
u64 usage;
int size = 0;
int i, j;
int i, j, size;
mutex_lock(&memcg->thresholds_lock);
if (type == _MEM)
thresholds = memcg->thresholds;
thresholds = &memcg->thresholds;
else if (type == _MEMSWAP)
thresholds = memcg->memsw_thresholds;
thresholds = &memcg->memsw_thresholds;
else
BUG();
@ -3664,53 +3653,45 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
__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 = 0;
for (i = 0; i < thresholds->primary->size; i++) {
if (thresholds->primary->entries[i].eventfd != eventfd)
size++;
}
/* Use preallocated buffer for new array of thresholds */
if (type == _MEM)
thresholds_new = memcg->__thresholds;
else
thresholds_new = memcg->__memsw_thresholds;
new = thresholds->spare;
/* Set thresholds array to NULL if we don't have thresholds */
if (!size) {
kfree(thresholds_new);
thresholds_new = NULL;
kfree(new);
new = NULL;
goto swap_buffers;
}
thresholds_new->size = size;
new->size = size;
/* Copy thresholds and find current threshold */
thresholds_new->current_threshold = -1;
for (i = 0, j = 0; i < thresholds->size; i++) {
if (thresholds->entries[i].eventfd == eventfd)
new->current_threshold = -1;
for (i = 0, j = 0; i < thresholds->primary->size; i++) {
if (thresholds->primary->entries[i].eventfd == eventfd)
continue;
thresholds_new->entries[j] = thresholds->entries[i];
if (thresholds_new->entries[j].threshold < usage) {
new->entries[j] = thresholds->primary->entries[i];
if (new->entries[j].threshold < usage) {
/*
* thresholds_new->current_threshold will not be used
* new->current_threshold will not be used
* until rcu_assign_pointer(), so it's safe to increment
* it here.
*/
++thresholds_new->current_threshold;
++new->current_threshold;
}
j++;
}
swap_buffers:
/* Swap thresholds array and preallocated buffer */
if (type == _MEM) {
memcg->__thresholds = thresholds;
rcu_assign_pointer(memcg->thresholds, thresholds_new);
} else {
memcg->__memsw_thresholds = thresholds;
rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new);
}
/* Swap primary and spare array */
thresholds->spare = thresholds->primary;
rcu_assign_pointer(thresholds->primary, new);
/* To be sure that nobody uses thresholds */
synchronize_rcu();