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staging: android: lowmemkiller: Substantially reduce overhead during reclaim

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This patch optimizes lowmemkiller to not do any work when it has an outstanding
kill-request. This greatly reduces the pressure on the task_list lock
(improving interactivity), as well as improving the vmscan performance
when under heavy memory pressure (by up to 20x in tests).

Note: For this enhancement to work, you need CONFIG_PROFILING

Signed-off-by: San Mehat <san@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
San Mehat 2010-05-05 11:38:42 -07:00 committed by Greg Kroah-Hartman
parent 4964cd41cd
commit 4755b72e26
1 changed files with 43 additions and 0 deletions
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43
drivers/staging/android/lowmemorykiller.c
View file

@ -34,6 +34,8 @@
#include <linux/mm.h>
#include <linux/oom.h>
#include <linux/sched.h>
#include <linux/profile.h>
#include <linux/notifier.h>
static uint32_t lowmem_debug_level = 2;
static int lowmem_adj[6] = {
@ -51,12 +53,32 @@ static size_t lowmem_minfree[6] = {
};
static int lowmem_minfree_size = 4;
static struct task_struct *lowmem_deathpending;
#define lowmem_print(level, x...) \
do { \
if (lowmem_debug_level >= (level)) \
printk(x); \
} while (0)
static int
task_notify_func(struct notifier_block *self, unsigned long val, void *data);
static struct notifier_block task_nb = {
.notifier_call = task_notify_func,
};
static int
task_notify_func(struct notifier_block *self, unsigned long val, void *data)
{
struct task_struct *task = data;
if (task == lowmem_deathpending) {
lowmem_deathpending = NULL;
task_handoff_unregister(&task_nb);
}
return NOTIFY_OK;
}
static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
{
struct task_struct *p;
@ -71,6 +93,18 @@ static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
int other_free = global_page_state(NR_FREE_PAGES);
int other_file = global_page_state(NR_FILE_PAGES);
/*
* If we already have a death outstanding, then
* bail out right away; indicating to vmscan
* that we have nothing further to offer on
* this pass.
*
* Note: Currently you need CONFIG_PROFILING
* for this to work correctly.
*/
if (lowmem_deathpending)
return 0;
if (lowmem_adj_size < array_size)
array_size = lowmem_adj_size;
if (lowmem_minfree_size < array_size)
@ -142,6 +176,15 @@ static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
selected->pid, selected->comm,
selected_oom_adj, selected_tasksize);
/*
* If CONFIG_PROFILING is off, then task_handoff_register()
* is a nop. In that case we don't want to stall the killer
* by setting lowmem_deathpending.
*/
#ifdef CONFIG_PROFILING
lowmem_deathpending = selected;
task_handoff_register(&task_nb);
#endif
force_sig(SIGKILL, selected);
rem -= selected_tasksize;
}