* Ingo Molnar <[EMAIL PROTECTED]> wrote:
> so .. how about the patch below? Note that we already had an "early
> bootup" special (the rq->idle check), it's now just made explicit via
> the scheduler_running flag.
the one below even builds. (untested otherwise)
Ingo
----------->
Subject: sched: make sched_clock() early-bootup capable
From: Ingo Molnar <[EMAIL PROTECTED]>
Date: Wed Feb 13 13:49:36 CET 2008
do not call sched_clock() too early. Not only might rq->idle
not be set up - but pure per-cpu data might not be accessible
either.
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
kernel/sched.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
Index: linux-x86.q/kernel/sched.c
===================================================================
--- linux-x86.q.orig/kernel/sched.c
+++ linux-x86.q/kernel/sched.c
@@ -666,6 +666,8 @@ const_debug unsigned int sysctl_sched_rt
*/
const_debug unsigned int sysctl_sched_rt_ratio = 62259;
+static __read_mostly int scheduler_running;
+
/*
* For kernel-internal use: high-speed (but slightly incorrect) per-cpu
* clock constructed from sched_clock():
@@ -676,14 +678,16 @@ unsigned long long cpu_clock(int cpu)
unsigned long flags;
struct rq *rq;
- local_irq_save(flags);
- rq = cpu_rq(cpu);
/*
* Only call sched_clock() if the scheduler has already been
* initialized (some code might call cpu_clock() very early):
*/
- if (rq->idle)
- update_rq_clock(rq);
+ if (unlikely(!scheduler_running))
+ return 0;
+
+ local_irq_save(flags);
+ rq = cpu_rq(cpu);
+ update_rq_clock(rq);
now = rq->clock;
local_irq_restore(flags);
@@ -7255,6 +7259,8 @@ void __init sched_init(void)
* During early bootup we pretend to be a normal task:
*/
current->sched_class = &fair_sched_class;
+
+ scheduler_running = 1;
}
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
--
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