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s390/tick: Remove CIF_NOHZ_DELAY flag

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Remove obsolete tick delay heuristic [1]. The upcoming cpuidle driver
handles frequent sleep/wakeup cycles more effectively.

[1] https://lore.kernel.org/all/20090929122533.402715150@de.ibm.com/

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Mete Durlu 2026-06-18 14:00:15 +02:00 committed by Vasily Gorbik
parent 0e3d3b4bb0
commit 71eabd104e
4 changed files with 0 additions and 10 deletions
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4
arch/s390/include/asm/processor.h
View File

@ -14,12 +14,10 @@
#include <linux/bits.h>
#define CIF_NOHZ_DELAY 2 /* delay HZ disable for a tick */
#define CIF_ENABLED_WAIT 5 /* in enabled wait state */
#define CIF_MCCK_GUEST 6 /* machine check happening in guest */
#define CIF_DEDICATED_CPU 7 /* this CPU is dedicated */
#define _CIF_NOHZ_DELAY BIT(CIF_NOHZ_DELAY)
#define _CIF_ENABLED_WAIT BIT(CIF_ENABLED_WAIT)
#define _CIF_MCCK_GUEST BIT(CIF_MCCK_GUEST)
#define _CIF_DEDICATED_CPU BIT(CIF_DEDICATED_CPU)
@ -97,8 +95,6 @@ static __always_inline bool test_cpu_flag_of(int flag, int cpu)
return test_bit(flag, &per_cpu(pcpu_devices, cpu).flags);
}
#define arch_needs_cpu() test_cpu_flag(CIF_NOHZ_DELAY)
static inline void get_cpu_id(struct cpuid *ptr)
{
asm volatile("stidp %0" : "=Q" (*ptr));

1
arch/s390/kernel/idle.c
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@ -136,7 +136,6 @@ void noinstr arch_cpu_idle(void)
/* Wait for external, I/O or machine check interrupt. */
psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT |
PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
clear_cpu_flag(CIF_NOHZ_DELAY);
set_cpu_flag(CIF_ENABLED_WAIT);
if (smp_cpu_mtid)
stcctm(MT_DIAG, smp_cpu_mtid, (u64 *)&idle->mt_cycles_enter);

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

@ -166,7 +166,6 @@ void noinstr do_io_irq(struct pt_regs *regs)
if (from_idle)
account_idle_time_irq();
set_cpu_flag(CIF_NOHZ_DELAY);
do {
regs->tpi_info = get_lowcore()->tpi_info;
if (get_lowcore()->tpi_info.adapter_IO)
@ -369,9 +368,6 @@ static irqreturn_t do_ext_interrupt(int irq, void *dummy)
int index;
ext_code.int_code = regs->int_code;
if (ext_code.code != EXT_IRQ_CLK_COMP)
set_cpu_flag(CIF_NOHZ_DELAY);
index = ext_hash(ext_code.code);
rcu_read_lock();
hlist_for_each_entry_rcu(p, &ext_int_hash[index], entry) {

1
arch/s390/kernel/smp.c
View File

@ -909,7 +909,6 @@ int __cpu_disable(void)
cregs[6].val &= ~0xff000000UL; /* disable all I/O interrupts */
cregs[14].val &= ~0x1f000000UL; /* disable most machine checks */
__local_ctl_load(0, 15, cregs);
clear_cpu_flag(CIF_NOHZ_DELAY);
return 0;
}