Commit ab96e798 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] boot cputime accounting 



Start the cpu time accounting very early to catch the cpu time spent
for the initial kernel setup. To make the output of /proc/uptime
match the sum of all cpu accounting values of the boot cpu reset
xtime and wall_to_monotonic to sane values based on the TOD clock.
The values set by timekeeping_init are off by up to a second.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent b6112ccb

arch/s390/kernel/head.S

+7 −1
Original line number Diff line number Diff line
@@ -473,7 +473,10 @@ startup:basr %r13,0 # get base 
	xc	0x300(256),0x300

	l	%r1,5f-.LPG0(%r13)

	stck	0(%r1)



	spt	6f-.LPG0(%r13)

	mvc	__LC_LAST_UPDATE_CLOCK(8),0(%r1)

	mvc	__LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)

	mvc	__LC_EXIT_TIMER(8),5f-.LPG0(%r13)

#ifndef CONFIG_MARCH_G5

	# check processor version against MARCH_{G5,Z900,Z990,Z9_109,Z10}

	stidp	__LC_CPUID		# store cpuid
@@ -500,8 +503,11 @@ startup:basr %r13,0 # get base 


	l	%r13,4f-.LPG0(%r13)

	b	0(%r13)

	.align	4

4:	.long	startup_continue

5:	.long	sched_clock_base_cc

	.align	8

6:	.long	0x7fffffff,0xffffffff



#

# params at 10400 (setup.h)

arch/s390/kernel/setup.c

+8 −0
Original line number Diff line number Diff line
@@ -434,6 +434,14 @@ setup_lowcore(void) 
#else

	lc->vdso_per_cpu_data = (unsigned long) &lc->paste[0];

#endif

	lc->sync_enter_timer = S390_lowcore.sync_enter_timer;

	lc->async_enter_timer = S390_lowcore.async_enter_timer;

	lc->exit_timer = S390_lowcore.exit_timer;

	lc->user_timer = S390_lowcore.user_timer;

	lc->system_timer = S390_lowcore.system_timer;

	lc->steal_timer = S390_lowcore.steal_timer;

	lc->last_update_timer = S390_lowcore.last_update_timer;

	lc->last_update_clock = S390_lowcore.last_update_clock;

	set_prefix((u32)(unsigned long) lc);

	lowcore_ptr[0] = lc;

}

arch/s390/kernel/time.c

+28 −8
Original line number Diff line number Diff line
@@ -253,32 +253,52 @@ void update_vsyscall_tz(void) 
 */

void __init time_init(void)

{

	struct timespec ts;

	unsigned long flags;

	cycle_t now;



	/* Reset time synchronization interfaces. */

	etr_reset();

	stp_reset();



	/* set xtime */

	tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &xtime);

        set_normalized_timespec(&wall_to_monotonic,

                                -xtime.tv_sec, -xtime.tv_nsec);



	/* request the clock comparator external interrupt */

	if (register_early_external_interrupt(0x1004,

					      clock_comparator_interrupt,

					      &ext_int_info_cc) != 0)

                panic("Couldn't request external interrupt 0x1004");



	if (clocksource_register(&clocksource_tod) != 0)

		panic("Could not register TOD clock source");



	/* request the timing alert external interrupt */

	if (register_early_external_interrupt(0x1406,

					      timing_alert_interrupt,

					      &ext_int_etr_cc) != 0)

		panic("Couldn't request external interrupt 0x1406");



	if (clocksource_register(&clocksource_tod) != 0)

		panic("Could not register TOD clock source");



	/*

	 * The TOD clock is an accurate clock. The xtime should be

	 * initialized in a way that the difference between TOD and

	 * xtime is reasonably small. Too bad that timekeeping_init

	 * sets xtime.tv_nsec to zero. In addition the clock source

	 * change from the jiffies clock source to the TOD clock

	 * source add another error of up to 1/HZ second. The same

	 * function sets wall_to_monotonic to a value that is too

	 * small for /proc/uptime to be accurate.

	 * Reset xtime and wall_to_monotonic to sane values.

	 */

	write_seqlock_irqsave(&xtime_lock, flags);

	now = get_clock();

	tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);

	clocksource_tod.cycle_last = now;

	clocksource_tod.raw_time = xtime;

	tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &ts);

	set_normalized_timespec(&wall_to_monotonic, -ts.tv_sec, -ts.tv_nsec);

	write_sequnlock_irqrestore(&xtime_lock, flags);



	/* Enable TOD clock interrupts on the boot cpu. */

	init_cpu_timer();



	/* Enable cpu timer interrupts on the boot cpu. */

	vtime_init();

}

arch/s390/kernel/vtime.c

+0 −8
Original line number Diff line number Diff line
@@ -527,16 +527,8 @@ EXPORT_SYMBOL(del_virt_timer); 
 */

void init_cpu_vtimer(void)

{

	struct thread_info *ti = current_thread_info();

	struct vtimer_queue *vq;



	S390_lowcore.user_timer = ti->user_timer;

	S390_lowcore.system_timer = ti->system_timer;



	/* kick the virtual timer */

	asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));

	asm volatile ("STPT %0" : "=m" (S390_lowcore.last_update_timer));



	/* initialize per cpu vtimer structure */

	vq = &__get_cpu_var(virt_cpu_timer);

	INIT_LIST_HEAD(&vq->list);

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