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Message-ID: <20070605075706.GA2496@elte.hu>
Date: Tue, 5 Jun 2007 09:57:06 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Balbir Singh <balbir@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Galbraith <efault@....de>,
Arjan van de Ven <arjan@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
pranith-kumar_d@...torg.com, Andi Kleen <andi@...stfloor.org>
Subject: Re: [patch] CFS scheduler, -v14
* Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> + /*
> + * Split up sched_exec_time according to the utime and
> + * stime ratio. At this point utime contains the summed
> + * sched_exec_runtime and stime is zero
> + */
> + if (sum_us_time) {
> + utime = ((tu_time * total_time) / sum_us_time);
> + stime = ((ts_time * total_time) / sum_us_time);
> + }
> + }
hm, Dmitry Adamushko found out that this will cause rounding problems
and might confuse 'top' - because total_time is a 10 msecs granular
value, so under the above calculation the total of 'utime+stime' can
shrink a bit as time goes forward. The symptom is that top will display
a '99.9%' entry for tasks, sporadically.
I've attached below my current delta (ontop of -v15) which does the
stime/utime splitup correctly and which includes some more enhancements
from Dmitry - could you please take a look at this and add any deltas
you might have ontop of it?
Ingo
---
Makefile | 2 +-
fs/proc/array.c | 33 ++++++++++++++++++++++++---------
include/linux/sched.h | 3 +--
kernel/posix-cpu-timers.c | 2 +-
kernel/sched.c | 17 ++++++++++-------
kernel/sched_debug.c | 16 +++++++++++++++-
kernel/sched_fair.c | 2 +-
kernel/sched_rt.c | 12 ++++++++----
8 files changed, 61 insertions(+), 26 deletions(-)
Index: linux/Makefile
===================================================================
--- linux.orig/Makefile
+++ linux/Makefile
@@ -1,7 +1,7 @@
VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 21
-EXTRAVERSION = .3-cfs-v15
+EXTRAVERSION = .3-cfs-v16
NAME = Nocturnal Monster Puppy
# *DOCUMENTATION*
Index: linux/fs/proc/array.c
===================================================================
--- linux.orig/fs/proc/array.c
+++ linux/fs/proc/array.c
@@ -172,8 +172,8 @@ static inline char * task_state(struct t
"Uid:\t%d\t%d\t%d\t%d\n"
"Gid:\t%d\t%d\t%d\t%d\n",
get_task_state(p),
- p->tgid, p->pid,
- pid_alive(p) ? rcu_dereference(p->real_parent)->tgid : 0,
+ p->tgid, p->pid,
+ pid_alive(p) ? rcu_dereference(p->real_parent)->tgid : 0,
pid_alive(p) && p->ptrace ? rcu_dereference(p->parent)->pid : 0,
p->uid, p->euid, p->suid, p->fsuid,
p->gid, p->egid, p->sgid, p->fsgid);
@@ -312,24 +312,39 @@ int proc_pid_status(struct task_struct *
static clock_t task_utime(struct task_struct *p)
{
+ clock_t utime = cputime_to_clock_t(p->utime),
+ total = utime + cputime_to_clock_t(p->stime);
+
/*
* Use CFS's precise accounting, if available:
*/
- if (!has_rt_policy(p) && !(sysctl_sched_load_smoothing & 128))
- return nsec_to_clock_t(p->sum_exec_runtime);
+ if (!(sysctl_sched_load_smoothing & 128)) {
+ u64 temp = (u64)nsec_to_clock_t(p->sum_exec_runtime);
+
+ if (total) {
+ temp *= utime;
+ do_div(temp, total);
+ }
+ utime = (clock_t)temp;
+ }
- return cputime_to_clock_t(p->utime);
+ return utime;
}
static clock_t task_stime(struct task_struct *p)
{
+ clock_t stime = cputime_to_clock_t(p->stime),
+ total = stime + cputime_to_clock_t(p->utime);
+
/*
- * Use CFS's precise accounting, if available:
+ * Use CFS's precise accounting, if available (we subtract
+ * utime from the total, to make sure the total observed
+ * by userspace grows monotonically - apps rely on that):
*/
- if (!has_rt_policy(p) && !(sysctl_sched_load_smoothing & 128))
- return 0;
+ if (!(sysctl_sched_load_smoothing & 128))
+ stime = nsec_to_clock_t(p->sum_exec_runtime) - task_utime(p);
- return cputime_to_clock_t(p->stime);
+ return stime;
}
Index: linux/include/linux/sched.h
===================================================================
--- linux.orig/include/linux/sched.h
+++ linux/include/linux/sched.h
@@ -852,7 +852,6 @@ struct task_struct {
u64 block_max;
u64 exec_max;
u64 wait_max;
- u64 last_ran;
s64 wait_runtime;
u64 sum_exec_runtime;
@@ -1235,7 +1234,7 @@ static inline int set_cpus_allowed(struc
extern unsigned long long sched_clock(void);
extern void sched_clock_unstable_event(void);
extern unsigned long long
-current_sched_runtime(const struct task_struct *current_task);
+task_sched_runtime(struct task_struct *task);
/* sched_exec is called by processes performing an exec */
#ifdef CONFIG_SMP
Index: linux/kernel/posix-cpu-timers.c
===================================================================
--- linux.orig/kernel/posix-cpu-timers.c
+++ linux/kernel/posix-cpu-timers.c
@@ -161,7 +161,7 @@ static inline cputime_t virt_ticks(struc
}
static inline unsigned long long sched_ns(struct task_struct *p)
{
- return (p == current) ? current_sched_runtime(p) : p->sum_exec_runtime;
+ return task_sched_runtime(p);
}
int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
Index: linux/kernel/sched.c
===================================================================
--- linux.orig/kernel/sched.c
+++ linux/kernel/sched.c
@@ -1227,7 +1227,7 @@ static void task_running_tick(struct rq
*/
static void __sched_fork(struct task_struct *p)
{
- p->wait_start_fair = p->wait_start = p->exec_start = p->last_ran = 0;
+ p->wait_start_fair = p->wait_start = p->exec_start = 0;
p->sum_exec_runtime = 0;
p->wait_runtime = 0;
@@ -2592,17 +2592,20 @@ DEFINE_PER_CPU(struct kernel_stat, kstat
EXPORT_PER_CPU_SYMBOL(kstat);
/*
- * Return current->sum_exec_runtime plus any more ns on the sched_clock
- * that have not yet been banked.
+ * Return p->sum_exec_runtime plus any more ns on the sched_clock
+ * that have not yet been banked in case the task is currently running.
*/
-unsigned long long current_sched_runtime(const struct task_struct *p)
+unsigned long long task_sched_runtime(struct task_struct *p)
{
unsigned long long ns;
unsigned long flags;
+ struct rq *rq;
- local_irq_save(flags);
- ns = p->sum_exec_runtime + sched_clock() - p->last_ran;
- local_irq_restore(flags);
+ rq = task_rq_lock(p, &flags);
+ ns = p->sum_exec_runtime;
+ if (rq->curr == p)
+ ns += rq_clock(rq) - p->exec_start;
+ task_rq_unlock(rq, &flags);
return ns;
}
Index: linux/kernel/sched_debug.c
===================================================================
--- linux.orig/kernel/sched_debug.c
+++ linux/kernel/sched_debug.c
@@ -188,6 +188,18 @@ __initcall(init_sched_debug_procfs);
void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
{
+ unsigned long flags;
+ int num_threads = 1;
+
+ rcu_read_lock();
+ if (lock_task_sighand(p, &flags)) {
+ num_threads = atomic_read(&p->signal->count);
+ unlock_task_sighand(p, &flags);
+ }
+ rcu_read_unlock();
+
+ SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, p->pid, num_threads);
+ SEQ_printf(m, "----------------------------------------------\n");
#define P(F) \
SEQ_printf(m, "%-25s:%20Ld\n", #F, (long long)p->F)
@@ -201,11 +213,13 @@ void proc_sched_show_task(struct task_st
P(block_max);
P(exec_max);
P(wait_max);
- P(last_ran);
P(wait_runtime);
P(wait_runtime_overruns);
P(wait_runtime_underruns);
P(sum_exec_runtime);
+ P(load_weight);
+ P(policy);
+ P(prio);
#undef P
{
Index: linux/kernel/sched_fair.c
===================================================================
--- linux.orig/kernel/sched_fair.c
+++ linux/kernel/sched_fair.c
@@ -200,7 +200,7 @@ static inline void update_curr(struct rq
* since the last time we changed raw_weighted_load:
*/
delta_exec = now - curr->exec_start;
- if (unlikely(delta_exec < 0))
+ if (unlikely((s64)delta_exec < 0))
delta_exec = 0;
if (unlikely(delta_exec > curr->exec_max))
curr->exec_max = delta_exec;
Index: linux/kernel/sched_rt.c
===================================================================
--- linux.orig/kernel/sched_rt.c
+++ linux/kernel/sched_rt.c
@@ -54,6 +54,7 @@ static void check_preempt_curr_rt(struct
static struct task_struct * pick_next_task_rt(struct rq *rq, u64 now)
{
struct prio_array *array = &rq->active;
+ struct task_struct *next;
struct list_head *queue;
int idx;
@@ -62,14 +63,17 @@ static struct task_struct * pick_next_ta
return NULL;
queue = array->queue + idx;
- return list_entry(queue->next, struct task_struct, run_list);
+ next = list_entry(queue->next, struct task_struct, run_list);
+
+ next->exec_start = now;
+
+ return next;
}
-/*
- * No accounting done when RT tasks are descheduled:
- */
static void put_prev_task_rt(struct rq *rq, struct task_struct *p, u64 now)
{
+ p->sum_exec_runtime += now - p->exec_start;
+ p->exec_start = 0;
}
/*
-
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