[PATCH] drivers: android: Restructure code in lowmemorykiller
Stratos Karafotis
stratosk at semaphore.gr
Thu Jan 31 21:32:06 UTC 2013
This patch restructures code for better readability and easier
maintenance.
Also introduces lowmemorykiller.h header file.
Signed-off-by: Stratos Karafotis <stratosk at semaphore.gr>
---
drivers/staging/android/lowmemorykiller.c | 162 ++++++++++++++++++------------
drivers/staging/android/lowmemorykiller.h | 42 ++++++++
2 files changed, 139 insertions(+), 65 deletions(-)
create mode 100644 drivers/staging/android/lowmemorykiller.h
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 3b91b0f..ade8584 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -38,50 +38,44 @@
#include <linux/rcupdate.h>
#include <linux/profile.h>
#include <linux/notifier.h>
+#include "lowmemorykiller.h"
-static uint32_t lowmem_debug_level = 2;
-static short lowmem_adj[6] = {
+static short lowmem_adj[LOWMEM_ARRAY_SIZE] = {
0,
1,
6,
12,
};
-static int lowmem_adj_size = 4;
-static int lowmem_minfree[6] = {
+static int lowmem_minfree[LOWMEM_ARRAY_SIZE] = {
3 * 512, /* 6MB */
2 * 1024, /* 8MB */
4 * 1024, /* 16MB */
16 * 1024, /* 64MB */
};
-static int lowmem_minfree_size = 4;
-static unsigned long lowmem_deathpending_timeout;
+static int lowmem_adj_size = DEF_LOWMEM_SIZE;
+static int lowmem_minfree_size = DEF_LOWMEM_SIZE;
+static uint32_t lowmem_debug_level = DEF_DEBUG_LEVEL;
-#define lowmem_print(level, x...) \
- do { \
- if (lowmem_debug_level >= (level)) \
- printk(x); \
- } while (0)
+static unsigned long lowmem_deathpending_timeout;
+static short min_score_adj;
+static struct selected_struct selected;
-static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
+static void set_min_score_adj(struct shrink_control *sc)
{
- struct task_struct *tsk;
- struct task_struct *selected = NULL;
- int rem = 0;
- int tasksize;
int i;
- short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
- int selected_tasksize = 0;
- short selected_oom_score_adj;
int array_size = ARRAY_SIZE(lowmem_adj);
int other_free = global_page_state(NR_FREE_PAGES);
int other_file = global_page_state(NR_FILE_PAGES) -
global_page_state(NR_SHMEM);
+ min_score_adj = OOM_SCORE_ADJ_MAX + 1;
+
if (lowmem_adj_size < array_size)
array_size = lowmem_adj_size;
if (lowmem_minfree_size < array_size)
array_size = lowmem_minfree_size;
+
for (i = 0; i < array_size; i++) {
if (other_free < lowmem_minfree[i] &&
other_file < lowmem_minfree[i]) {
@@ -89,10 +83,82 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
break;
}
}
+
if (sc->nr_to_scan > 0)
lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %hd\n",
sc->nr_to_scan, sc->gfp_mask, other_free,
other_file, min_score_adj);
+ return;
+}
+
+static enum lowmem_scan_t scan_process(struct task_struct *tsk)
+{
+ struct task_struct *p;
+ short oom_score_adj;
+ int tasksize;
+
+ if (tsk->flags & PF_KTHREAD)
+ return LMK_SCAN_CONTINUE;
+
+ p = find_lock_task_mm(tsk);
+ if (!p)
+ return LMK_SCAN_CONTINUE;
+
+ if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
+ time_before_eq(jiffies, lowmem_deathpending_timeout)) {
+ task_unlock(p);
+ rcu_read_unlock();
+ return LMK_SCAN_ABORT;
+ }
+
+ oom_score_adj = p->signal->oom_score_adj;
+ if (oom_score_adj < min_score_adj) {
+ task_unlock(p);
+ return LMK_SCAN_CONTINUE;
+ }
+
+ tasksize = get_mm_rss(p->mm);
+ task_unlock(p);
+ if (tasksize <= 0)
+ return LMK_SCAN_CONTINUE;
+
+ if (selected.task) {
+ if (oom_score_adj < selected.oom_score_adj)
+ return LMK_SCAN_CONTINUE;
+
+ if (oom_score_adj == selected.oom_score_adj &&
+ tasksize <= selected.tasksize)
+ return LMK_SCAN_CONTINUE;
+ }
+
+ selected.task = p;
+ selected.tasksize = tasksize;
+ selected.oom_score_adj = oom_score_adj;
+ lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n",
+ p->pid, p->comm, oom_score_adj, tasksize);
+
+ return LMK_SCAN_OK;
+}
+
+static inline void kill_selected(void)
+{
+ lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
+ selected.task->pid, selected.task->comm,
+ selected.oom_score_adj, selected.tasksize);
+
+ lowmem_deathpending_timeout = jiffies + HZ;
+
+ send_sig(SIGKILL, selected.task, 0);
+ set_tsk_thread_flag(selected.task, TIF_MEMDIE);
+}
+
+static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
+{
+ struct task_struct *tsk;
+ int rem = 0;
+
+ set_min_score_adj(sc);
+
rem = global_page_state(NR_ACTIVE_ANON) +
global_page_state(NR_ACTIVE_FILE) +
global_page_state(NR_INACTIVE_ANON) +
@@ -102,60 +168,27 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
sc->nr_to_scan, sc->gfp_mask, rem);
return rem;
}
- selected_oom_score_adj = min_score_adj;
- rcu_read_lock();
- for_each_process(tsk) {
- struct task_struct *p;
- short oom_score_adj;
+ selected.task = NULL;
+ selected.tasksize = 0;
+ selected.oom_score_adj = min_score_adj;
- if (tsk->flags & PF_KTHREAD)
- continue;
-
- p = find_lock_task_mm(tsk);
- if (!p)
- continue;
+ rcu_read_lock();
- if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
- time_before_eq(jiffies, lowmem_deathpending_timeout)) {
- task_unlock(p);
- rcu_read_unlock();
+ for_each_process(tsk) {
+ if (scan_process(tsk) == LMK_SCAN_ABORT)
return 0;
- }
- oom_score_adj = p->signal->oom_score_adj;
- if (oom_score_adj < min_score_adj) {
- task_unlock(p);
- continue;
- }
- tasksize = get_mm_rss(p->mm);
- task_unlock(p);
- if (tasksize <= 0)
- continue;
- if (selected) {
- if (oom_score_adj < selected_oom_score_adj)
- continue;
- if (oom_score_adj == selected_oom_score_adj &&
- tasksize <= selected_tasksize)
- continue;
- }
- selected = p;
- selected_tasksize = tasksize;
- selected_oom_score_adj = oom_score_adj;
- lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n",
- p->pid, p->comm, oom_score_adj, tasksize);
}
- if (selected) {
- lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
- selected->pid, selected->comm,
- selected_oom_score_adj, selected_tasksize);
- lowmem_deathpending_timeout = jiffies + HZ;
- send_sig(SIGKILL, selected, 0);
- set_tsk_thread_flag(selected, TIF_MEMDIE);
- rem -= selected_tasksize;
+
+ if (selected.task) {
+ kill_selected();
+ rem -= selected.tasksize;
}
+
lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
sc->nr_to_scan, sc->gfp_mask, rem);
rcu_read_unlock();
+
return rem;
}
@@ -186,4 +219,3 @@ module_init(lowmem_init);
module_exit(lowmem_exit);
MODULE_LICENSE("GPL");
-
diff --git a/drivers/staging/android/lowmemorykiller.h b/drivers/staging/android/lowmemorykiller.h
new file mode 100644
index 0000000..923ccf7
--- /dev/null
+++ b/drivers/staging/android/lowmemorykiller.h
@@ -0,0 +1,42 @@
+/* include/linux/lowmemorykiller.h
+ *
+ * Copyright (C) 2008 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _LINUX_LOWMEMORYKILLER_H
+#define _LINUX_LOWMEMORYKILLER_H
+
+#define DEF_DEBUG_LEVEL (2)
+#define DEF_LOWMEM_SIZE (4)
+#define LOWMEM_ARRAY_SIZE (6)
+
+#define lowmem_print(level, x...) \
+ do { \
+ if (lowmem_debug_level >= (level)) \
+ printk(x); \
+ } while (0)
+
+enum lowmem_scan_t {
+ LMK_SCAN_OK,
+ LMK_SCAN_CONTINUE,
+ LMK_SCAN_ABORT,
+};
+
+/* Selected task struct */
+struct selected_struct {
+ struct task_struct *task;
+ int tasksize;
+ short oom_score_adj;
+};
+
+#endif /* _LINUX_LOWMEMORYKILLER_H */
--
1.8.1
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