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[S390] Convert s390 to GENERIC_CLOCKEVENTS.

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This way we get rid of s390's NO_IDLE_HZ and use the generic dynticks
variant instead. In addition we get high resolution timers for free.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
This commit is contained in:
Heiko Carstens 2008-04-17 07:46:25 +02:00
parent d7b906897e
commit 5a62b19219
9 changed files with 98 additions and 228 deletions
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24
arch/s390/Kconfig
View File

@ -43,6 +43,9 @@ config GENERIC_HWEIGHT
config GENERIC_TIME
def_bool y
config GENERIC_CLOCKEVENTS
def_bool y
config GENERIC_BUG
bool
depends on BUG
@ -73,6 +76,8 @@ menu "Base setup"
comment "Processor type and features"
source "kernel/time/Kconfig"
config 64BIT
bool "64 bit kernel"
help
@ -487,25 +492,6 @@ config APPLDATA_NET_SUM
source kernel/Kconfig.hz
config NO_IDLE_HZ
bool "No HZ timer ticks in idle"
help
Switches the regular HZ timer off when the system is going idle.
This helps z/VM to detect that the Linux system is idle. VM can
then "swap-out" this guest which reduces memory usage. It also
reduces the overhead of idle systems.
The HZ timer can be switched on/off via /proc/sys/kernel/hz_timer.
hz_timer=0 means HZ timer is disabled. hz_timer=1 means HZ
timer is active.
config NO_IDLE_HZ_INIT
bool "HZ timer in idle off by default"
depends on NO_IDLE_HZ
help
The HZ timer is switched off in idle by default. That means the
HZ timer is already disabled at boot time.
config S390_HYPFS_FS
bool "s390 hypervisor file system support"
select SYS_HYPERVISOR

4
arch/s390/kernel/process.c
View File

@ -36,6 +36,7 @@
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/utsname.h>
#include <linux/tick.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@ -167,9 +168,10 @@ static void default_idle(void)
void cpu_idle(void)
{
for (;;) {
tick_nohz_stop_sched_tick();
while (!need_resched())
default_idle();
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();

9
arch/s390/kernel/s390_ext.c
View File

@ -120,12 +120,9 @@ void do_extint(struct pt_regs *regs, unsigned short code)
old_regs = set_irq_regs(regs);
irq_enter();
s390_idle_check();
if (S390_lowcore.int_clock >= S390_lowcore.jiffy_timer)
/**
* Make sure that the i/o interrupt did not "overtake"
* the last HZ timer interrupt.
*/
account_ticks(S390_lowcore.int_clock);
if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
/* Serve timer interrupts first. */
clock_comparator_work();
kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
index = ext_hash(code);
for (p = ext_int_hash[index]; p; p = p->next) {

2
arch/s390/kernel/setup.c
View File

@ -428,7 +428,7 @@ setup_lowcore(void)
lc->io_new_psw.mask = psw_kernel_bits;
lc->io_new_psw.addr = PSW_ADDR_AMODE | (unsigned long) io_int_handler;
lc->ipl_device = S390_lowcore.ipl_device;
lc->jiffy_timer = -1LL;
lc->clock_comparator = -1ULL;
lc->kernel_stack = ((unsigned long) &init_thread_union) + THREAD_SIZE;
lc->async_stack = (unsigned long)
__alloc_bootmem(ASYNC_SIZE, ASYNC_SIZE, 0) + ASYNC_SIZE;

256
arch/s390/kernel/time.c
View File

@ -30,7 +30,7 @@
#include <linux/timex.h>
#include <linux/notifier.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <asm/uaccess.h>
#include <asm/delay.h>
#include <asm/s390_ext.h>
@ -57,9 +57,9 @@
static ext_int_info_t ext_int_info_cc;
static ext_int_info_t ext_int_etr_cc;
static u64 init_timer_cc;
static u64 jiffies_timer_cc;
static u64 xtime_cc;
static DEFINE_PER_CPU(struct clock_event_device, comparators);
/*
* Scheduler clock - returns current time in nanosec units.
@ -95,162 +95,40 @@ void tod_to_timeval(__u64 todval, struct timespec *xtime)
#define s390_do_profile() do { ; } while(0)
#endif /* CONFIG_PROFILING */
/*
* Advance the per cpu tick counter up to the time given with the
* "time" argument. The per cpu update consists of accounting
* the virtual cpu time, calling update_process_times and calling
* the profiling hook. If xtime is before time it is advanced as well.
*/
void account_ticks(u64 time)
void clock_comparator_work(void)
{
__u32 ticks;
__u64 tmp;
/* Calculate how many ticks have passed. */
if (time < S390_lowcore.jiffy_timer)
return;
tmp = time - S390_lowcore.jiffy_timer;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) { /* more than two ticks ? */
ticks = __div(tmp, CLK_TICKS_PER_JIFFY) + 1;
S390_lowcore.jiffy_timer +=
CLK_TICKS_PER_JIFFY * (__u64) ticks;
} else if (tmp >= CLK_TICKS_PER_JIFFY) {
ticks = 2;
S390_lowcore.jiffy_timer += 2*CLK_TICKS_PER_JIFFY;
} else {
ticks = 1;
S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
}
#ifdef CONFIG_SMP
/*
* Do not rely on the boot cpu to do the calls to do_timer.
* Spread it over all cpus instead.
*/
write_seqlock(&xtime_lock);
if (S390_lowcore.jiffy_timer > xtime_cc) {
__u32 xticks;
tmp = S390_lowcore.jiffy_timer - xtime_cc;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) {
xticks = __div(tmp, CLK_TICKS_PER_JIFFY);
xtime_cc += (__u64) xticks * CLK_TICKS_PER_JIFFY;
} else {
xticks = 1;
xtime_cc += CLK_TICKS_PER_JIFFY;
}
do_timer(xticks);
}
write_sequnlock(&xtime_lock);
#else
do_timer(ticks);
#endif
while (ticks--)
update_process_times(user_mode(get_irq_regs()));
struct clock_event_device *cd;
S390_lowcore.clock_comparator = -1ULL;
set_clock_comparator(S390_lowcore.clock_comparator);
cd = &__get_cpu_var(comparators);
cd->event_handler(cd);
s390_do_profile();
}
#ifdef CONFIG_NO_IDLE_HZ
#ifdef CONFIG_NO_IDLE_HZ_INIT
int sysctl_hz_timer = 0;
#else
int sysctl_hz_timer = 1;
#endif
/*
* Stop the HZ tick on the current CPU.
* Only cpu_idle may call this function.
* Fixup the clock comparator.
*/
static void stop_hz_timer(void)
static void fixup_clock_comparator(unsigned long long delta)
{
unsigned long flags;
unsigned long seq, next;
__u64 timer, todval;
int cpu = smp_processor_id();
if (sysctl_hz_timer != 0)
/* If nobody is waiting there's nothing to fix. */
if (S390_lowcore.clock_comparator == -1ULL)
return;
cpu_set(cpu, nohz_cpu_mask);
/*
* Leave the clock comparator set up for the next timer
* tick if either rcu or a softirq is pending.
*/
if (rcu_needs_cpu(cpu) || local_softirq_pending()) {
cpu_clear(cpu, nohz_cpu_mask);
return;
}
/*
* This cpu is going really idle. Set up the clock comparator
* for the next event.
*/
next = next_timer_interrupt();
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
timer = ((__u64) next) - ((__u64) jiffies) + jiffies_64;
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
todval = -1ULL;
/* Be careful about overflows. */
if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {
timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
if (timer >= jiffies_timer_cc)
todval = timer;
}
set_clock_comparator(todval);
S390_lowcore.clock_comparator += delta;
set_clock_comparator(S390_lowcore.clock_comparator);
}
/*
* Start the HZ tick on the current CPU.
* Only cpu_idle may call this function.
*/
static void start_hz_timer(void)
static int s390_next_event(unsigned long delta,
struct clock_event_device *evt)
{
if (!cpu_isset(smp_processor_id(), nohz_cpu_mask))
return;
account_ticks(get_clock());
set_clock_comparator(S390_lowcore.jiffy_timer + CPU_DEVIATION);
cpu_clear(smp_processor_id(), nohz_cpu_mask);
S390_lowcore.clock_comparator = get_clock() + delta;
set_clock_comparator(S390_lowcore.clock_comparator);
return 0;
}
static int nohz_idle_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
static void s390_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
switch (action) {
case S390_CPU_IDLE:
stop_hz_timer();
break;
case S390_CPU_NOT_IDLE:
start_hz_timer();
break;
}
return NOTIFY_OK;
}
static struct notifier_block nohz_idle_nb = {
.notifier_call = nohz_idle_notify,
};
static void __init nohz_init(void)
{
if (register_idle_notifier(&nohz_idle_nb))
panic("Couldn't register idle notifier");
}
#endif
/*
* Set up per cpu jiffy timer and set the clock comparator.
*/
static void setup_jiffy_timer(void)
{
/* Set up clock comparator to next jiffy. */
S390_lowcore.jiffy_timer =
jiffies_timer_cc + (jiffies_64 + 1) * CLK_TICKS_PER_JIFFY;
set_clock_comparator(S390_lowcore.jiffy_timer + CPU_DEVIATION);
}
/*
@ -259,7 +137,26 @@ static void setup_jiffy_timer(void)
*/
void init_cpu_timer(void)
{
setup_jiffy_timer();
struct clock_event_device *cd;
int cpu;
S390_lowcore.clock_comparator = -1ULL;
set_clock_comparator(S390_lowcore.clock_comparator);
cpu = smp_processor_id();
cd = &per_cpu(comparators, cpu);
cd->name = "comparator";
cd->features = CLOCK_EVT_FEAT_ONESHOT;
cd->mult = 16777;
cd->shift = 12;
cd->min_delta_ns = 1;
cd->max_delta_ns = LONG_MAX;
cd->rating = 400;
cd->cpumask = cpumask_of_cpu(cpu);
cd->set_next_event = s390_next_event;
cd->set_mode = s390_set_mode;
clockevents_register_device(cd);
/* Enable clock comparator timer interrupt. */
__ctl_set_bit(0,11);
@ -270,8 +167,6 @@ void init_cpu_timer(void)
static void clock_comparator_interrupt(__u16 code)
{
/* set clock comparator for next tick */
set_clock_comparator(S390_lowcore.jiffy_timer + CPU_DEVIATION);
}
static void etr_reset(void);
@ -316,8 +211,9 @@ static struct clocksource clocksource_tod = {
*/
void __init time_init(void)
{
u64 init_timer_cc;
init_timer_cc = reset_tod_clock();
xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY;
jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY;
/* set xtime */
@ -342,10 +238,6 @@ void __init time_init(void)
/* Enable TOD clock interrupts on the boot cpu. */
init_cpu_timer();
#ifdef CONFIG_NO_IDLE_HZ
nohz_init();
#endif
#ifdef CONFIG_VIRT_TIMER
vtime_init();
#endif
@ -699,53 +591,49 @@ static int etr_aib_follows(struct etr_aib *a1, struct etr_aib *a2, int p)
}
/*
* The time is "clock". xtime is what we think the time is.
* The time is "clock". old is what we think the time is.
* Adjust the value by a multiple of jiffies and add the delta to ntp.
* "delay" is an approximation how long the synchronization took. If
* the time correction is positive, then "delay" is subtracted from
* the time difference and only the remaining part is passed to ntp.
*/
static void etr_adjust_time(unsigned long long clock, unsigned long long delay)
static unsigned long long etr_adjust_time(unsigned long long old,
unsigned long long clock,
unsigned long long delay)
{
unsigned long long delta, ticks;
struct timex adjust;
/*
* We don't have to take the xtime lock because the cpu
* executing etr_adjust_time is running disabled in
* tasklet context and all other cpus are looping in
* etr_sync_cpu_start.
*/
if (clock > xtime_cc) {
if (clock > old) {
/* It is later than we thought. */
delta = ticks = clock - xtime_cc;
delta = ticks = clock - old;
delta = ticks = (delta < delay) ? 0 : delta - delay;
delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
init_timer_cc = init_timer_cc + delta;
jiffies_timer_cc = jiffies_timer_cc + delta;
xtime_cc = xtime_cc + delta;
adjust.offset = ticks * (1000000 / HZ);
} else {
/* It is earlier than we thought. */
delta = ticks = xtime_cc - clock;
delta = ticks = old - clock;
delta -= do_div(ticks, CLK_TICKS_PER_JIFFY);
init_timer_cc = init_timer_cc - delta;
jiffies_timer_cc = jiffies_timer_cc - delta;
xtime_cc = xtime_cc - delta;
delta = -delta;
adjust.offset = -ticks * (1000000 / HZ);
}
jiffies_timer_cc += delta;
if (adjust.offset != 0) {
printk(KERN_NOTICE "etr: time adjusted by %li micro-seconds\n",
adjust.offset);
adjust.modes = ADJ_OFFSET_SINGLESHOT;
do_adjtimex(&adjust);
}
return delta;
}
static struct {
int in_sync;
unsigned long long fixup_cc;
} etr_sync;
static void etr_sync_cpu_start(void *dummy)
{
int *in_sync = dummy;
etr_enable_sync_clock();
/*
* This looks like a busy wait loop but it isn't. etr_sync_cpus
@ -753,7 +641,7 @@ static void etr_sync_cpu_start(void *dummy)
* __udelay will stop the cpu on an enabled wait psw until the
* TOD is running again.
*/
while (*in_sync == 0) {
while (etr_sync.in_sync == 0) {
__udelay(1);
/*
* A different cpu changes *in_sync. Therefore use
@ -761,14 +649,14 @@ static void etr_sync_cpu_start(void *dummy)
*/
barrier();
}
if (*in_sync != 1)
if (etr_sync.in_sync != 1)
/* Didn't work. Clear per-cpu in sync bit again. */
etr_disable_sync_clock(NULL);
/*
* This round of TOD syncing is done. Set the clock comparator
* to the next tick and let the processor continue.
*/
setup_jiffy_timer();
fixup_clock_comparator(etr_sync.fixup_cc);
}
static void etr_sync_cpu_end(void *dummy)
@ -783,8 +671,8 @@ static void etr_sync_cpu_end(void *dummy)
static int etr_sync_clock(struct etr_aib *aib, int port)
{
struct etr_aib *sync_port;
unsigned long long clock, delay;
int in_sync, follows;
unsigned long long clock, old_clock, delay, delta;
int follows;
int rc;
/* Check if the current aib is adjacent to the sync port aib. */
@ -799,9 +687,9 @@ static int etr_sync_clock(struct etr_aib *aib, int port)
* successfully synced the clock. smp_call_function will
* return after all other cpus are in etr_sync_cpu_start.
*/
in_sync = 0;
memset(&etr_sync, 0, sizeof(etr_sync));
preempt_disable();
smp_call_function(etr_sync_cpu_start,&in_sync,0,0);
smp_call_function(etr_sync_cpu_start, NULL, 0, 0);
local_irq_disable();
etr_enable_sync_clock();
@ -809,6 +697,7 @@ static int etr_sync_clock(struct etr_aib *aib, int port)
__ctl_set_bit(14, 21);
__ctl_set_bit(0, 29);
clock = ((unsigned long long) (aib->edf2.etv + 1)) << 32;
old_clock = get_clock();
if (set_clock(clock) == 0) {
__udelay(1); /* Wait for the clock to start. */
__ctl_clear_bit(0, 29);
@ -817,16 +706,17 @@ static int etr_sync_clock(struct etr_aib *aib, int port)
/* Adjust Linux timing variables. */
delay = (unsigned long long)
(aib->edf2.etv - sync_port->edf2.etv) << 32;
etr_adjust_time(clock, delay);
setup_jiffy_timer();
delta = etr_adjust_time(old_clock, clock, delay);
etr_sync.fixup_cc = delta;
fixup_clock_comparator(delta);
/* Verify that the clock is properly set. */
if (!etr_aib_follows(sync_port, aib, port)) {
/* Didn't work. */
etr_disable_sync_clock(NULL);
in_sync = -EAGAIN;
etr_sync.in_sync = -EAGAIN;
rc = -EAGAIN;
} else {
in_sync = 1;
etr_sync.in_sync = 1;
rc = 0;
}
} else {
@ -834,7 +724,7 @@ static int etr_sync_clock(struct etr_aib *aib, int port)
__ctl_clear_bit(0, 29);
__ctl_clear_bit(14, 21);
etr_disable_sync_clock(NULL);
in_sync = -EAGAIN;
etr_sync.in_sync = -EAGAIN;
rc = -EAGAIN;
}
local_irq_enable();

14
arch/s390/lib/delay.c
View File

@ -34,7 +34,7 @@ void __delay(unsigned long loops)
*/
void __udelay(unsigned long usecs)
{
u64 end, time, jiffy_timer = 0;
u64 end, time, old_cc = 0;
unsigned long flags, cr0, mask, dummy;
int irq_context;
@ -43,8 +43,8 @@ void __udelay(unsigned long usecs)
local_bh_disable();
local_irq_save(flags);
if (raw_irqs_disabled_flags(flags)) {
jiffy_timer = S390_lowcore.jiffy_timer;
S390_lowcore.jiffy_timer = -1ULL - (4096 << 12);
old_cc = S390_lowcore.clock_comparator;
S390_lowcore.clock_comparator = -1ULL;
__ctl_store(cr0, 0, 0);
dummy = (cr0 & 0xffff00e0) | 0x00000800;
__ctl_load(dummy , 0, 0);
@ -55,8 +55,8 @@ void __udelay(unsigned long usecs)
end = get_clock() + ((u64) usecs << 12);
do {
time = end < S390_lowcore.jiffy_timer ?
end : S390_lowcore.jiffy_timer;
time = end < S390_lowcore.clock_comparator ?
end : S390_lowcore.clock_comparator;
set_clock_comparator(time);
trace_hardirqs_on();
__load_psw_mask(mask);
@ -65,10 +65,10 @@ void __udelay(unsigned long usecs)
if (raw_irqs_disabled_flags(flags)) {
__ctl_load(cr0, 0, 0);
S390_lowcore.jiffy_timer = jiffy_timer;
S390_lowcore.clock_comparator = old_cc;
}
if (!irq_context)
_local_bh_enable();
set_clock_comparator(S390_lowcore.jiffy_timer);
set_clock_comparator(S390_lowcore.clock_comparator);
local_irq_restore(flags);
}

9
drivers/s390/cio/cio.c
View File

@ -651,12 +651,9 @@ do_IRQ (struct pt_regs *regs)
old_regs = set_irq_regs(regs);
irq_enter();
s390_idle_check();
if (S390_lowcore.int_clock >= S390_lowcore.jiffy_timer)
/**
* Make sure that the i/o interrupt did not "overtake"
* the last HZ timer interrupt.
*/
account_ticks(S390_lowcore.int_clock);
if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
/* Serve timer interrupts first. */
clock_comparator_work();
/*
* Get interrupt information from lowcore
*/

2
include/asm-s390/hardirq.h
View File

@ -32,6 +32,6 @@ typedef struct {
#define HARDIRQ_BITS 8
extern void account_ticks(u64 time);
void clock_comparator_work(void);
#endif /* __ASM_HARDIRQ_H */

6
include/asm-s390/lowcore.h
View File

@ -80,7 +80,6 @@
#define __LC_CPUID 0xC60
#define __LC_CPUADDR 0xC68
#define __LC_IPLDEV 0xC7C
#define __LC_JIFFY_TIMER 0xC80
#define __LC_CURRENT 0xC90
#define __LC_INT_CLOCK 0xC98
#else /* __s390x__ */
@ -103,7 +102,6 @@
#define __LC_CPUID 0xD80
#define __LC_CPUADDR 0xD88
#define __LC_IPLDEV 0xDB8
#define __LC_JIFFY_TIMER 0xDC0
#define __LC_CURRENT 0xDD8
#define __LC_INT_CLOCK 0xDE8
#endif /* __s390x__ */
@ -276,7 +274,7 @@ struct _lowcore
/* entry.S sensitive area end */
/* SMP info area: defined by DJB */
__u64 jiffy_timer; /* 0xc80 */
__u64 clock_comparator; /* 0xc80 */
__u32 ext_call_fast; /* 0xc88 */
__u32 percpu_offset; /* 0xc8c */
__u32 current_task; /* 0xc90 */
@ -368,7 +366,7 @@ struct _lowcore
/* entry.S sensitive area end */
/* SMP info area: defined by DJB */
__u64 jiffy_timer; /* 0xdc0 */
__u64 clock_comparator; /* 0xdc0 */
__u64 ext_call_fast; /* 0xdc8 */
__u64 percpu_offset; /* 0xdd0 */
__u64 current_task; /* 0xdd8 */