Commit 32bd671d authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

signal: re-add dead task accumulation stats. 



We're going to split the process wide cpu accounting into two parts:

 - clocks; which can take all the time they want since they run
           from user context.

 - timers; which need constant time tracing but can affort the overhead
           because they're default off -- and rare.

The clock readout will go back to a full sum of the thread group, for this
we need to re-add the exit stats that were removed in the initial itimer
rework (f06febc9: timers: fix itimer/many thread hang).

Furthermore, since that full sum can be rather slow for large thread groups
and we have the complete dead task stats, revert the do_notify_parent time
computation.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 83895147

include/linux/sched.h

+9 −1
Original line number Diff line number Diff line
@@ -559,7 +559,7 @@ struct signal_struct { 
	 * Live threads maintain their own counters and add to these

	 * in __exit_signal, except for the group leader.

	 */

	cputime_t cutime, cstime;

	cputime_t utime, stime, cutime, cstime;

	cputime_t gtime;

	cputime_t cgtime;

	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
@@ -567,6 +567,14 @@ struct signal_struct { 
	unsigned long inblock, oublock, cinblock, coublock;

	struct task_io_accounting ioac;



	/*

	 * Cumulative ns of schedule CPU time fo dead threads in the

	 * group, not including a zombie group leader, (This only differs

	 * from jiffies_to_ns(utime + stime) if sched_clock uses something

	 * other than jiffies.)

	 */

	unsigned long long sum_sched_runtime;



	/*

	 * We don't bother to synchronize most readers of this at all,

	 * because there is no reader checking a limit that actually needs

kernel/exit.c

+3 −0
Original line number Diff line number Diff line
@@ -118,6 +118,8 @@ static void __exit_signal(struct task_struct *tsk) 
		 * We won't ever get here for the group leader, since it

		 * will have been the last reference on the signal_struct.

		 */

		sig->utime = cputime_add(sig->utime, task_utime(tsk));

		sig->stime = cputime_add(sig->stime, task_stime(tsk));

		sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));

		sig->min_flt += tsk->min_flt;

		sig->maj_flt += tsk->maj_flt;
@@ -126,6 +128,7 @@ static void __exit_signal(struct task_struct *tsk) 
		sig->inblock += task_io_get_inblock(tsk);

		sig->oublock += task_io_get_oublock(tsk);

		task_io_accounting_add(&sig->ioac, &tsk->ioac);

		sig->sum_sched_runtime += tsk->se.sum_exec_runtime;

		sig = NULL; /* Marker for below. */

	}

kernel/fork.c

+2 −1
Original line number Diff line number Diff line
@@ -851,13 +851,14 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 
	sig->tty_old_pgrp = NULL;

	sig->tty = NULL;



	sig->cutime = sig->cstime = cputime_zero;

	sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;

	sig->gtime = cputime_zero;

	sig->cgtime = cputime_zero;

	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;

	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;

	sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;

	task_io_accounting_init(&sig->ioac);

	sig->sum_sched_runtime = 0;

	taskstats_tgid_init(sig);



	task_lock(current->group_leader);

kernel/signal.c

+4 −4
Original line number Diff line number Diff line
@@ -1367,7 +1367,6 @@ int do_notify_parent(struct task_struct *tsk, int sig) 
	struct siginfo info;

	unsigned long flags;

	struct sighand_struct *psig;

	struct task_cputime cputime;

	int ret = sig;



	BUG_ON(sig == -1);
@@ -1397,9 +1396,10 @@ int do_notify_parent(struct task_struct *tsk, int sig) 
	info.si_uid = __task_cred(tsk)->uid;

	rcu_read_unlock();



	thread_group_cputime(tsk, &cputime);

	info.si_utime = cputime_to_jiffies(cputime.utime);

	info.si_stime = cputime_to_jiffies(cputime.stime);

	info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,

				tsk->signal->utime));

	info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,

				tsk->signal->stime));



	info.si_status = tsk->exit_code & 0x7f;

	if (tsk->exit_code & 0x80)

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