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Merge branch 'idle-vtime-fixes-cleanups' into fixes

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Pull a small idle/vtime series with two cputime accounting fixes plus
related cleanups and minor improvements.

* idle-vtime-fixes-cleanups:
  s390/idle: Remove psw_idle() prototype
  s390/vtime: Use lockdep_assert_irqs_disabled() instead of BUG_ON()
  s390/vtime: Use __this_cpu_read() / get rid of READ_ONCE()
  s390/irq/idle: Remove psw bits early
  s390/idle: Inline update_timer_idle()
  s390/idle: Slightly optimize idle time accounting
  s390/idle: Add comment for non obvious code
  s390/vtime: Fix virtual timer forwarding
  s390/idle: Fix cpu idle exit cpu time accounting

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2026-02-25 16:59:16 +01:00
commit 05c58a6605
6 changed files with 63 additions and 64 deletions
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4
arch/s390/include/asm/idle.h
View File

@ -19,9 +19,9 @@ struct s390_idle_data {
unsigned long mt_cycles_enter[8];
};
DECLARE_PER_CPU(struct s390_idle_data, s390_idle);
extern struct device_attribute dev_attr_idle_count;
extern struct device_attribute dev_attr_idle_time_us;
void psw_idle(struct s390_idle_data *data, unsigned long psw_mask);
#endif /* _S390_IDLE_H */

34
arch/s390/include/asm/vtime.h
View File

@ -2,6 +2,12 @@
#ifndef _S390_VTIME_H
#define _S390_VTIME_H
#include <asm/lowcore.h>
#include <asm/cpu_mf.h>
#include <asm/idle.h>
DECLARE_PER_CPU(u64, mt_cycles[8]);
static inline void update_timer_sys(void)
{
struct lowcore *lc = get_lowcore();
@ -20,4 +26,32 @@ static inline void update_timer_mcck(void)
lc->last_update_timer = lc->mcck_enter_timer;
}
static inline void update_timer_idle(void)
{
struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
struct lowcore *lc = get_lowcore();
u64 cycles_new[8];
int i, mtid;
mtid = smp_cpu_mtid;
if (mtid) {
stcctm(MT_DIAG, mtid, cycles_new);
for (i = 0; i < mtid; i++)
__this_cpu_add(mt_cycles[i], cycles_new[i] - idle->mt_cycles_enter[i]);
}
/*
* This is a bit subtle: Forward last_update_clock so it excludes idle
* time. For correct steal time calculation in do_account_vtime() add
* passed wall time before idle_enter to steal_timer:
* During the passed wall time before idle_enter CPU time may have
* been accounted to system, hardirq, softirq, etc. lowcore fields.
* The accounted CPU times will be subtracted again from steal_timer
* when accumulated steal time is calculated in do_account_vtime().
*/
lc->steal_timer += idle->clock_idle_enter - lc->last_update_clock;
lc->last_update_clock = lc->int_clock;
lc->system_timer += lc->last_update_timer - idle->timer_idle_enter;
lc->last_update_timer = lc->sys_enter_timer;
}
#endif /* _S390_VTIME_H */

2
arch/s390/kernel/entry.h
View File

@ -56,8 +56,6 @@ long sys_s390_pci_mmio_write(unsigned long, const void __user *, size_t);
long sys_s390_pci_mmio_read(unsigned long, void __user *, size_t);
long sys_s390_sthyi(unsigned long function_code, void __user *buffer, u64 __user *return_code, unsigned long flags);
DECLARE_PER_CPU(u64, mt_cycles[8]);
unsigned long stack_alloc(void);
void stack_free(unsigned long stack);

25
arch/s390/kernel/idle.c
View File

@ -15,37 +15,22 @@
#include <trace/events/power.h>
#include <asm/cpu_mf.h>
#include <asm/cputime.h>
#include <asm/idle.h>
#include <asm/nmi.h>
#include <asm/smp.h>
#include "entry.h"
static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
void account_idle_time_irq(void)
{
struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
struct lowcore *lc = get_lowcore();
unsigned long idle_time;
u64 cycles_new[8];
int i;
if (smp_cpu_mtid) {
stcctm(MT_DIAG, smp_cpu_mtid, cycles_new);
for (i = 0; i < smp_cpu_mtid; i++)
this_cpu_add(mt_cycles[i], cycles_new[i] - idle->mt_cycles_enter[i]);
}
idle_time = lc->int_clock - idle->clock_idle_enter;
lc->steal_timer += idle->clock_idle_enter - lc->last_update_clock;
lc->last_update_clock = lc->int_clock;
lc->system_timer += lc->last_update_timer - idle->timer_idle_enter;
lc->last_update_timer = lc->sys_enter_timer;
idle_time = get_lowcore()->int_clock - idle->clock_idle_enter;
/* Account time spent with enabled wait psw loaded as idle time. */
WRITE_ONCE(idle->idle_time, READ_ONCE(idle->idle_time) + idle_time);
WRITE_ONCE(idle->idle_count, READ_ONCE(idle->idle_count) + 1);
__atomic64_add(idle_time, &idle->idle_time);
__atomic64_add_const(1, &idle->idle_count);
account_idle_time(cputime_to_nsecs(idle_time));
}

20
arch/s390/kernel/irq.c
View File

@ -146,6 +146,12 @@ void noinstr do_io_irq(struct pt_regs *regs)
struct pt_regs *old_regs = set_irq_regs(regs);
bool from_idle;
from_idle = test_and_clear_cpu_flag(CIF_ENABLED_WAIT);
if (from_idle) {
update_timer_idle();
regs->psw.mask &= ~(PSW_MASK_EXT | PSW_MASK_IO | PSW_MASK_WAIT);
}
irq_enter_rcu();
if (user_mode(regs)) {
@ -154,7 +160,6 @@ void noinstr do_io_irq(struct pt_regs *regs)
current->thread.last_break = regs->last_break;
}
from_idle = test_and_clear_cpu_flag(CIF_ENABLED_WAIT);
if (from_idle)
account_idle_time_irq();
@ -171,9 +176,6 @@ void noinstr do_io_irq(struct pt_regs *regs)
set_irq_regs(old_regs);
irqentry_exit(regs, state);
if (from_idle)
regs->psw.mask &= ~(PSW_MASK_EXT | PSW_MASK_IO | PSW_MASK_WAIT);
}
void noinstr do_ext_irq(struct pt_regs *regs)
@ -182,6 +184,12 @@ void noinstr do_ext_irq(struct pt_regs *regs)
struct pt_regs *old_regs = set_irq_regs(regs);
bool from_idle;
from_idle = test_and_clear_cpu_flag(CIF_ENABLED_WAIT);
if (from_idle) {
update_timer_idle();
regs->psw.mask &= ~(PSW_MASK_EXT | PSW_MASK_IO | PSW_MASK_WAIT);
}
irq_enter_rcu();
if (user_mode(regs)) {
@ -194,7 +202,6 @@ void noinstr do_ext_irq(struct pt_regs *regs)
regs->int_parm = get_lowcore()->ext_params;
regs->int_parm_long = get_lowcore()->ext_params2;
from_idle = test_and_clear_cpu_flag(CIF_ENABLED_WAIT);
if (from_idle)
account_idle_time_irq();
@ -203,9 +210,6 @@ void noinstr do_ext_irq(struct pt_regs *regs)
irq_exit_rcu();
set_irq_regs(old_regs);
irqentry_exit(regs, state);
if (from_idle)
regs->psw.mask &= ~(PSW_MASK_EXT | PSW_MASK_IO | PSW_MASK_WAIT);
}
static void show_msi_interrupt(struct seq_file *p, int irq)

42
arch/s390/kernel/vtime.c
View File

@ -48,8 +48,7 @@ static inline void set_vtimer(u64 expires)
static inline int virt_timer_forward(u64 elapsed)
{
BUG_ON(!irqs_disabled());
lockdep_assert_irqs_disabled();
if (list_empty(&virt_timer_list))
return 0;
elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
@ -137,23 +136,16 @@ static int do_account_vtime(struct task_struct *tsk)
lc->system_timer += timer;
/* Update MT utilization calculation */
if (smp_cpu_mtid &&
time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
if (smp_cpu_mtid && time_after64(jiffies_64, __this_cpu_read(mt_scaling_jiffies)))
update_mt_scaling();
/* Calculate cputime delta */
user = update_tsk_timer(&tsk->thread.user_timer,
READ_ONCE(lc->user_timer));
guest = update_tsk_timer(&tsk->thread.guest_timer,
READ_ONCE(lc->guest_timer));
system = update_tsk_timer(&tsk->thread.system_timer,
READ_ONCE(lc->system_timer));
hardirq = update_tsk_timer(&tsk->thread.hardirq_timer,
READ_ONCE(lc->hardirq_timer));
softirq = update_tsk_timer(&tsk->thread.softirq_timer,
READ_ONCE(lc->softirq_timer));
lc->steal_timer +=
clock - user - guest - system - hardirq - softirq;
user = update_tsk_timer(&tsk->thread.user_timer, lc->user_timer);
guest = update_tsk_timer(&tsk->thread.guest_timer, lc->guest_timer);
system = update_tsk_timer(&tsk->thread.system_timer, lc->system_timer);
hardirq = update_tsk_timer(&tsk->thread.hardirq_timer, lc->hardirq_timer);
softirq = update_tsk_timer(&tsk->thread.softirq_timer, lc->softirq_timer);
lc->steal_timer += clock - user - guest - system - hardirq - softirq;
/* Push account value */
if (user) {
@ -225,10 +217,6 @@ static u64 vtime_delta(void)
return timer - lc->last_update_timer;
}
/*
* Update process times based on virtual cpu times stored by entry.S
* to the lowcore fields user_timer, system_timer & steal_clock.
*/
void vtime_account_kernel(struct task_struct *tsk)
{
struct lowcore *lc = get_lowcore();
@ -238,27 +226,17 @@ void vtime_account_kernel(struct task_struct *tsk)
lc->guest_timer += delta;
else
lc->system_timer += delta;
virt_timer_forward(delta);
}
EXPORT_SYMBOL_GPL(vtime_account_kernel);
void vtime_account_softirq(struct task_struct *tsk)
{
u64 delta = vtime_delta();
get_lowcore()->softirq_timer += delta;
virt_timer_forward(delta);
get_lowcore()->softirq_timer += vtime_delta();
}
void vtime_account_hardirq(struct task_struct *tsk)
{
u64 delta = vtime_delta();
get_lowcore()->hardirq_timer += delta;
virt_timer_forward(delta);
get_lowcore()->hardirq_timer += vtime_delta();
}
/*