[PATCH 2/5] 2.6.0 sched fork cleanup

Nick Piggin
2003-12-20T15:20:47Z

[-- Attachment #1: Type: text/plain, Size: 83 bytes --]

Move some fork related scheduler policy from fork.c to sched.c where it
belongs.

[-- Attachment #2: sched-fork-cleanup.patch --]
[-- Type: text/plain, Size: 3752 bytes --]

Move some fork related scheduler policy from fork.c to sched.c where it belongs.

linux-2.6-npiggin/include/linux/sched.h | 1
linux-2.6-npiggin/kernel/fork.c | 30 ++-------------------------
linux-2.6-npiggin/kernel/sched.c | 35 ++++++++++++++++++++++++++++++++
3 files changed, 39 insertions(+), 27 deletions(-)

diff -puN include/linux/sched.h~sched-fork-cleanup include/linux/sched.h
--- linux-2.6/include/linux/sched.h~sched-fork-cleanup 2003-12-19 14:22:29.000000000 +1100
+++ linux-2.6-npiggin/include/linux/sched.h 2003-12-19 14:22:29.000000000 +1100
@@ -580,6 +580,7 @@ extern int FASTCALL(wake_up_process(stru
static inline void kick_process(struct task_struct *tsk) { }
#endif
extern void FASTCALL(wake_up_forked_process(struct task_struct * tsk));
+extern void FASTCALL(sched_fork(task_t * p));
extern void FASTCALL(sched_exit(task_t * p));

asmlinkage long sys_wait4(pid_t pid,unsigned int * stat_addr, int options, struct rusage * ru);
diff -puN kernel/fork.c~sched-fork-cleanup kernel/fork.c
--- linux-2.6/kernel/fork.c~sched-fork-cleanup 2003-12-19 14:22:29.000000000 +1100
+++ linux-2.6-npiggin/kernel/fork.c 2003-12-19 14:22:29.000000000 +1100
@@ -973,33 +973,9 @@ struct task_struct *copy_process(unsigne
p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
p->pdeath_signal = 0;

- /*
- * Share the timeslice between parent and child, thus the
- * total amount of pending timeslices in the system doesn't change,
- * resulting in more scheduling fairness.
- */
- local_irq_disable();
- p->time_slice = (current->time_slice + 1) >> 1;
- /*
- * The remainder of the first timeslice might be recovered by
- * the parent if the child exits early enough.
- */
- p->first_time_slice = 1;
- current->time_slice >>= 1;
- p->timestamp = sched_clock();
- if (!current->time_slice) {
- /*
- * This case is rare, it happens when the parent has only
- * a single jiffy left from its timeslice. Taking the
- * runqueue lock is not a problem.
- */
- current->time_slice = 1;
- preempt_disable();
- scheduler_tick(0, 0);
- local_irq_enable();
- preempt_enable();
- } else
- local_irq_enable();
+ /* Perform scheduler related accounting */
+ sched_fork(p);
+
/*
* Ok, add it to the run-queues and make it
* visible to the rest of the system.
diff -puN kernel/sched.c~sched-fork-cleanup kernel/sched.c
--- linux-2.6/kernel/sched.c~sched-fork-cleanup 2003-12-19 14:22:29.000000000 +1100
+++ linux-2.6-npiggin/kernel/sched.c 2003-12-19 14:22:29.000000000 +1100
@@ -674,6 +674,41 @@ int wake_up_state(task_t *p, unsigned in
}

/*
+ * Perform scheduler related accounting for a newly forked process p.
+ * p is forked by current.
+ */
+void sched_fork(task_t *p)
+{
+ /*
+ * Share the timeslice between parent and child, thus the
+ * total amount of pending timeslices in the system doesn't change,
+ * resulting in more scheduling fairness.
+ */
+ local_irq_disable();
+ p->time_slice = (current->time_slice + 1) >> 1;
+ /*
+ * The remainder of the first timeslice might be recovered by
+ * the parent if the child exits early enough.
+ */
+ p->first_time_slice = 1;
+ current->time_slice >>= 1;
+ p->timestamp = sched_clock();
+ if (!current->time_slice) {
+ /*
+ * This case is rare, it happens when the parent has only
+ * a single jiffy left from its timeslice. Taking the
+ * runqueue lock is not a problem.
+ */
+ current->time_slice = 1;
+ preempt_disable();
+ scheduler_tick(0, 0);
+ local_irq_enable();
+ preempt_enable();
+ } else
+ local_irq_enable();
+}
+
+/*
* wake_up_forked_process - wake up a freshly forked process.
*
* This function will do some initial scheduler statistics housekeeping

_