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Date: Fri, 2 Jul 2010 14:49:41 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc: LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
Minchan Kim <minchan.kim@...il.com>,
David Rientjes <rientjes@...gle.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 10/11] oom: give the dying task a higher priority
On Wed, 30 Jun 2010 18:33:23 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> wrote:
> +static void boost_dying_task_prio(struct task_struct *p,
> + struct mem_cgroup *mem)
> +{
> + struct sched_param param = { .sched_priority = 1 };
> +
> + if (mem)
> + return;
> +
> + if (!rt_task(p))
> + sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m);
> +}
We can actually make `param' static here. That saves a teeny bit of
code and a little bit of stack. The oom-killer can be called when
we're using a lot of stack.
But if we make that change we really should make the param arg to
sched_setscheduler_nocheck() be const. I did that (and was able to
convert lots of callers to use a static `param') but to complete the
job we'd need to chase through all the security goop, fixing up
security_task_setscheduler() and callees, and I got bored.
include/linux/sched.h | 2 +-
kernel/kthread.c | 2 +-
kernel/sched.c | 4 ++--
kernel/softirq.c | 4 +++-
kernel/stop_machine.c | 2 +-
kernel/workqueue.c | 2 +-
6 files changed, 9 insertions(+), 7 deletions(-)
diff -puN kernel/kthread.c~a kernel/kthread.c
--- a/kernel/kthread.c~a
+++ a/kernel/kthread.c
@@ -131,7 +131,7 @@ struct task_struct *kthread_create(int (
wait_for_completion(&create.done);
if (!IS_ERR(create.result)) {
- struct sched_param param = { .sched_priority = 0 };
+ static struct sched_param param = { .sched_priority = 0 };
va_list args;
va_start(args, namefmt);
diff -puN kernel/workqueue.c~a kernel/workqueue.c
--- a/kernel/workqueue.c~a
+++ a/kernel/workqueue.c
@@ -962,7 +962,7 @@ init_cpu_workqueue(struct workqueue_stru
static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
{
- struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+ static struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
struct workqueue_struct *wq = cwq->wq;
const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d";
struct task_struct *p;
diff -puN kernel/stop_machine.c~a kernel/stop_machine.c
--- a/kernel/stop_machine.c~a
+++ a/kernel/stop_machine.c
@@ -291,7 +291,7 @@ repeat:
static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
- struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
+ static struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
unsigned int cpu = (unsigned long)hcpu;
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
struct task_struct *p;
diff -puN kernel/sched.c~a kernel/sched.c
--- a/kernel/sched.c~a
+++ a/kernel/sched.c
@@ -4570,7 +4570,7 @@ static bool check_same_owner(struct task
}
static int __sched_setscheduler(struct task_struct *p, int policy,
- struct sched_param *param, bool user)
+ const struct sched_param *param, bool user)
{
int retval, oldprio, oldpolicy = -1, on_rq, running;
unsigned long flags;
@@ -4734,7 +4734,7 @@ EXPORT_SYMBOL_GPL(sched_setscheduler);
* but our caller might not have that capability.
*/
int sched_setscheduler_nocheck(struct task_struct *p, int policy,
- struct sched_param *param)
+ const struct sched_param *param)
{
return __sched_setscheduler(p, policy, param, false);
}
diff -puN kernel/softirq.c~a kernel/softirq.c
--- a/kernel/softirq.c~a
+++ a/kernel/softirq.c
@@ -827,7 +827,9 @@ static int __cpuinit cpu_callback(struct
cpumask_any(cpu_online_mask));
case CPU_DEAD:
case CPU_DEAD_FROZEN: {
- struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+ static struct sched_param param = {
+ .sched_priority = MAX_RT_PRIO-1,
+ };
p = per_cpu(ksoftirqd, hotcpu);
per_cpu(ksoftirqd, hotcpu) = NULL;
diff -puN include/linux/sched.h~a include/linux/sched.h
--- a/include/linux/sched.h~a
+++ a/include/linux/sched.h
@@ -1924,7 +1924,7 @@ extern int task_curr(const struct task_s
extern int idle_cpu(int cpu);
extern int sched_setscheduler(struct task_struct *, int, struct sched_param *);
extern int sched_setscheduler_nocheck(struct task_struct *, int,
- struct sched_param *);
+ const struct sched_param *);
extern struct task_struct *idle_task(int cpu);
extern struct task_struct *curr_task(int cpu);
extern void set_curr_task(int cpu, struct task_struct *p);
_
--
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