timers: fix itimer/many thread hang, v2
This is the second resubmission of the posix timer rework patch, posted
a few days ago.
This includes the changes from the previous resubmittion, which addressed
Oleg Nesterov's comments, removing the RCU stuff from the patch and
un-inlining the thread_group_cputime() function for SMP.
In addition, per Ingo Molnar it simplifies the UP code, consolidating much
of it with the SMP version and depending on lower-level SMP/UP handling to
take care of the differences.
It also cleans up some UP compile errors, moves the scheduler stats-related
macros into kernel/sched_stats.h, cleans up a merge error in
kernel/fork.c and has a few other minor fixes and cleanups as suggested
by Oleg and Ingo. Thanks for the review, guys.
Signed-off-by: Frank Mayhar <fmayhar@google.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7ce8d4e..b982fb4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -454,15 +454,9 @@
* This structure contains the version of task_cputime, above, that is
* used for thread group CPU clock calculations.
*/
-#ifdef CONFIG_SMP
struct thread_group_cputime {
struct task_cputime *totals;
};
-#else
-struct thread_group_cputime {
- struct task_cputime totals;
-};
-#endif
/*
* NOTE! "signal_struct" does not have it's own
@@ -2124,195 +2118,28 @@
/*
* Thread group CPU time accounting.
*/
-#ifdef CONFIG_SMP
-extern int thread_group_cputime_alloc_smp(struct task_struct *);
-extern void thread_group_cputime_smp(struct task_struct *, struct task_cputime *);
+extern int thread_group_cputime_alloc(struct task_struct *);
+extern void thread_group_cputime(struct task_struct *, struct task_cputime *);
static inline void thread_group_cputime_init(struct signal_struct *sig)
{
sig->cputime.totals = NULL;
}
-static inline int thread_group_cputime_clone_thread(struct task_struct *curr,
- struct task_struct *new)
+static inline int thread_group_cputime_clone_thread(struct task_struct *curr)
{
if (curr->signal->cputime.totals)
return 0;
- return thread_group_cputime_alloc_smp(curr);
+ return thread_group_cputime_alloc(curr);
}
+
static inline void thread_group_cputime_free(struct signal_struct *sig)
{
free_percpu(sig->cputime.totals);
}
-/**
- * thread_group_cputime - Sum the thread group time fields across all CPUs.
- *
- * This is a wrapper for the real routine, thread_group_cputime_smp(). See
- * that routine for details.
- */
-static inline void thread_group_cputime(
- struct task_struct *tsk,
- struct task_cputime *times)
-{
- thread_group_cputime_smp(tsk, times);
-}
-
-/**
- * thread_group_cputime_account_user - Maintain utime for a thread group.
- *
- * @tgtimes: Pointer to thread_group_cputime structure.
- * @cputime: Time value by which to increment the utime field of that
- * structure.
- *
- * If thread group time is being maintained, get the structure for the
- * running CPU and update the utime field there.
- */
-static inline void thread_group_cputime_account_user(
- struct thread_group_cputime *tgtimes,
- cputime_t cputime)
-{
- if (tgtimes->totals) {
- struct task_cputime *times;
-
- times = per_cpu_ptr(tgtimes->totals, get_cpu());
- times->utime = cputime_add(times->utime, cputime);
- put_cpu_no_resched();
- }
-}
-
-/**
- * thread_group_cputime_account_system - Maintain stime for a thread group.
- *
- * @tgtimes: Pointer to thread_group_cputime structure.
- * @cputime: Time value by which to increment the stime field of that
- * structure.
- *
- * If thread group time is being maintained, get the structure for the
- * running CPU and update the stime field there.
- */
-static inline void thread_group_cputime_account_system(
- struct thread_group_cputime *tgtimes,
- cputime_t cputime)
-{
- if (tgtimes->totals) {
- struct task_cputime *times;
-
- times = per_cpu_ptr(tgtimes->totals, get_cpu());
- times->stime = cputime_add(times->stime, cputime);
- put_cpu_no_resched();
- }
-}
-
-/**
- * thread_group_cputime_account_exec_runtime - Maintain exec runtime for a
- * thread group.
- *
- * @tgtimes: Pointer to thread_group_cputime structure.
- * @ns: Time value by which to increment the sum_exec_runtime field
- * of that structure.
- *
- * If thread group time is being maintained, get the structure for the
- * running CPU and update the sum_exec_runtime field there.
- */
-static inline void thread_group_cputime_account_exec_runtime(
- struct thread_group_cputime *tgtimes,
- unsigned long long ns)
-{
- if (tgtimes->totals) {
- struct task_cputime *times;
-
- times = per_cpu_ptr(tgtimes->totals, get_cpu());
- times->sum_exec_runtime += ns;
- put_cpu_no_resched();
- }
-}
-
-#else /* CONFIG_SMP */
-
-static inline void thread_group_cputime_init(struct signal_struct *sig)
-{
- sig->cputime.totals.utime = cputime_zero;
- sig->cputime.totals.stime = cputime_zero;
- sig->cputime.totals.sum_exec_runtime = 0;
-}
-
-static inline int thread_group_cputime_alloc(struct task_struct *tsk)
-{
- return 0;
-}
-
-static inline void thread_group_cputime_free(struct signal_struct *sig)
-{
-}
-
-static inline int thread_group_cputime_clone_thread(struct task_struct *curr,
- struct task_struct *tsk)
-{
- return 0;
-}
-
-static inline void thread_group_cputime(struct task_struct *tsk,
- struct task_cputime *cputime)
-{
- *cputime = tsk->signal->cputime.totals;
-}
-
-static inline void thread_group_cputime_account_user(
- struct thread_group_cputime *tgtimes,
- cputime_t cputime)
-{
- tgtimes->totals.utime = cputime_add(tgtimes->totals.utime, cputime);
-}
-
-static inline void thread_group_cputime_account_system(
- struct thread_group_cputime *tgtimes,
- cputime_t cputime)
-{
- tgtimes->totals.stime = cputime_add(tgtimes->totals.stime, cputime);
-}
-
-static inline void thread_group_cputime_account_exec_runtime(
- struct thread_group_cputime *tgtimes,
- unsigned long long ns)
-{
- tgtimes->totals.sum_exec_runtime += ns;
-}
-
-#endif /* CONFIG_SMP */
-
-static inline void account_group_user_time(struct task_struct *tsk,
- cputime_t cputime)
-{
- struct signal_struct *sig;
-
- sig = tsk->signal;
- if (likely(sig))
- thread_group_cputime_account_user(&sig->cputime, cputime);
-}
-
-static inline void account_group_system_time(struct task_struct *tsk,
- cputime_t cputime)
-{
- struct signal_struct *sig;
-
- sig = tsk->signal;
- if (likely(sig))
- thread_group_cputime_account_system(&sig->cputime, cputime);
-}
-
-static inline void account_group_exec_runtime(struct task_struct *tsk,
- unsigned long long ns)
-{
- struct signal_struct *sig;
-
- sig = tsk->signal;
- if (likely(sig))
- thread_group_cputime_account_exec_runtime(&sig->cputime, ns);
-}
-
/*
* Reevaluate whether the task has signals pending delivery.
* Wake the task if so.