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Message-Id: <200704221340.02349.kernel@kolivas.org>
Date: Sun, 22 Apr 2007 13:40:01 +1000
From: Con Kolivas <kernel@...ivas.org>
To: linux kernel mailing list <linux-kernel@...r.kernel.org>,
ck list <ck@....kolivas.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Willy Tarreau <w@....eu>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH] sched: implement staircase deadline scheduler ymf accounting fixes
This causes significant improvements on SMP hardware. I don't think the kernel
should be -nicing X by itself; that should be a sysadmin choice so I won't
be including that change in the SD patches. The following change will be in
the next release of SD (v0.45).
Andrew Please apply on top of yaf-fix
---
SMP balancing broke on converting time_slice to usecs.
update_cpu_clock is unnecessarily complex and doesn't allow sub usec values.
Thanks to Willy Tarreau <w@....eu> for picking up SMP idle anomalies.
Signed-off-by: Con Kolivas <kernel@...ivas.org>
---
kernel/sched.c | 42 +++++++++++++++++-------------------------
1 file changed, 17 insertions(+), 25 deletions(-)
Index: linux-2.6.21-rc7-sd/kernel/sched.c
===================================================================
--- linux-2.6.21-rc7-sd.orig/kernel/sched.c 2007-04-21 22:50:31.000000000 +1000
+++ linux-2.6.21-rc7-sd/kernel/sched.c 2007-04-22 13:29:29.000000000 +1000
@@ -88,12 +88,10 @@ unsigned long long __attribute__((weak))
#define SCHED_PRIO(p) ((p)+MAX_RT_PRIO)
/* Some helpers for converting to/from various scales.*/
-#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
+#define MS_TO_NS(TIME) ((TIME) * 1000000)
#define MS_TO_US(TIME) ((TIME) * 1000)
-/* Can return 0 */
-#define MS_TO_JIFFIES(TIME) ((TIME) * HZ / 1000)
-#define JIFFIES_TO_MS(TIME) ((TIME) * 1000 / HZ)
+#define US_TO_MS(TIME) ((TIME) / 1000)
#define TASK_PREEMPTS_CURR(p, curr) ((p)->prio < (curr)->prio)
@@ -876,29 +874,28 @@ static void requeue_task(struct task_str
/*
* task_timeslice - the total duration a task can run during one major
- * rotation. Returns value in jiffies.
+ * rotation. Returns value in milliseconds as the smallest value can be 1.
*/
-static inline int task_timeslice(struct task_struct *p)
+static int task_timeslice(struct task_struct *p)
{
- int slice;
+ int slice = p->quota; /* quota is in us */
- slice = NS_TO_JIFFIES(p->quota);
if (!rt_task(p))
slice += (PRIO_RANGE - 1 - TASK_USER_PRIO(p)) * slice;
- return slice;
+ return US_TO_MS(slice);
}
/*
* Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
* If static_prio_timeslice() is ever changed to break this assumption then
- * this code will need modification
+ * this code will need modification. Scaled as multiples of milliseconds.
*/
#define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
#define LOAD_WEIGHT(lp) \
(((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
#define TASK_LOAD_WEIGHT(p) LOAD_WEIGHT(task_timeslice(p))
#define RTPRIO_TO_LOAD_WEIGHT(rp) \
- (LOAD_WEIGHT((MS_TO_JIFFIES(rr_interval) + 20 + (rp))))
+ (LOAD_WEIGHT((rr_interval + 20 + (rp))))
static void set_load_weight(struct task_struct *p)
{
@@ -3035,32 +3032,27 @@ static void
update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now,
int tick)
{
- cputime64_t time_diff = now - p->last_ran;
- const unsigned int min_diff = 1000;
- int us_time_diff;
+ long time_diff = now - p->last_ran;
if (tick) {
/*
* Called from scheduler_tick() there should be less than two
* jiffies worth, and not negative/overflow.
*/
- if (time_diff > JIFFIES_TO_NS(2) || time_diff < min_diff)
+ if (time_diff > JIFFIES_TO_NS(2) || time_diff < 0)
time_diff = JIFFIES_TO_NS(1);
} else {
/*
* Called from context_switch there should be less than one
- * jiffy worth, and not negative/overflowed. In the case when
- * sched_clock fails to return high resolution values this
- * also ensures at least 1 min_diff gets banked.
+ * jiffy worth, and not negative/overflow. There should be
+ * some time banked here so use a nominal 1ms.
*/
- if (time_diff > JIFFIES_TO_NS(1) || time_diff < min_diff)
- time_diff = min_diff;
+ if (time_diff > JIFFIES_TO_NS(1) || time_diff < 1)
+ time_diff = 1000;
}
/* time_slice accounting is done in usecs to avoid overflow on 32bit */
- us_time_diff = time_diff;
- us_time_diff /= 1000;
if (p != rq->idle && p->policy != SCHED_FIFO)
- p->time_slice -= us_time_diff;
+ p->time_slice -= time_diff / 1000;
p->sched_time += time_diff;
p->last_ran = rq->most_recent_timestamp = now;
}
@@ -4636,8 +4628,8 @@ long sys_sched_rr_get_interval(pid_t pid
if (retval)
goto out_unlock;
- jiffies_to_timespec(p->policy == SCHED_FIFO ?
- 0 : task_timeslice(p), &t);
+ t = ns_to_timespec(p->policy == SCHED_FIFO ? 0 :
+ MS_TO_NS(task_timeslice(p)));
read_unlock(&tasklist_lock);
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
out_nounlock:
--
-ck
-
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