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x86/percpu: Move preempt_count next to current_task

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Add preempt_count to pcpu_hot, since it is once of the most used
per-cpu variables.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111145.284170644@infradead.org
This commit is contained in:
Thomas Gleixner 2022-09-15 13:11:02 +02:00 committed by Peter Zijlstra
parent e57ef2ed97
commit 64701838bf
3 changed files with 16 additions and 20 deletions
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1
arch/x86/include/asm/current.h
View File

@ -15,6 +15,7 @@ struct pcpu_hot {
union {
struct {
struct task_struct *current_task;
int preempt_count;
};
u8 pad[64];
};

27
arch/x86/include/asm/preempt.h
View File

@ -4,11 +4,11 @@
#include <asm/rmwcc.h>
#include <asm/percpu.h>
#include <asm/current.h>
#include <linux/thread_info.h>
#include <linux/static_call_types.h>
DECLARE_PER_CPU(int, __preempt_count);
/* We use the MSB mostly because its available */
#define PREEMPT_NEED_RESCHED 0x80000000
@ -24,7 +24,7 @@ DECLARE_PER_CPU(int, __preempt_count);
*/
static __always_inline int preempt_count(void)
{
return raw_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED;
return raw_cpu_read_4(pcpu_hot.preempt_count) & ~PREEMPT_NEED_RESCHED;
}
static __always_inline void preempt_count_set(int pc)
@ -32,10 +32,10 @@ static __always_inline void preempt_count_set(int pc)
int old, new;
do {
old = raw_cpu_read_4(__preempt_count);
old = raw_cpu_read_4(pcpu_hot.preempt_count);
new = (old & PREEMPT_NEED_RESCHED) |
(pc & ~PREEMPT_NEED_RESCHED);
} while (raw_cpu_cmpxchg_4(__preempt_count, old, new) != old);
} while (raw_cpu_cmpxchg_4(pcpu_hot.preempt_count, old, new) != old);
}
/*
@ -44,7 +44,7 @@ static __always_inline void preempt_count_set(int pc)
#define init_task_preempt_count(p) do { } while (0)
#define init_idle_preempt_count(p, cpu) do { \
per_cpu(__preempt_count, (cpu)) = PREEMPT_DISABLED; \
per_cpu(pcpu_hot.preempt_count, (cpu)) = PREEMPT_DISABLED; \
} while (0)
/*
@ -58,17 +58,17 @@ static __always_inline void preempt_count_set(int pc)
static __always_inline void set_preempt_need_resched(void)
{
raw_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED);
raw_cpu_and_4(pcpu_hot.preempt_count, ~PREEMPT_NEED_RESCHED);
}
static __always_inline void clear_preempt_need_resched(void)
{
raw_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED);
raw_cpu_or_4(pcpu_hot.preempt_count, PREEMPT_NEED_RESCHED);
}
static __always_inline bool test_preempt_need_resched(void)
{
return !(raw_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED);
return !(raw_cpu_read_4(pcpu_hot.preempt_count) & PREEMPT_NEED_RESCHED);
}
/*
@ -77,12 +77,12 @@ static __always_inline bool test_preempt_need_resched(void)
static __always_inline void __preempt_count_add(int val)
{
raw_cpu_add_4(__preempt_count, val);
raw_cpu_add_4(pcpu_hot.preempt_count, val);
}
static __always_inline void __preempt_count_sub(int val)
{
raw_cpu_add_4(__preempt_count, -val);
raw_cpu_add_4(pcpu_hot.preempt_count, -val);
}
/*
@ -92,7 +92,8 @@ static __always_inline void __preempt_count_sub(int val)
*/
static __always_inline bool __preempt_count_dec_and_test(void)
{
return GEN_UNARY_RMWcc("decl", __preempt_count, e, __percpu_arg([var]));
return GEN_UNARY_RMWcc("decl", pcpu_hot.preempt_count, e,
__percpu_arg([var]));
}
/*
@ -100,7 +101,7 @@ static __always_inline bool __preempt_count_dec_and_test(void)
*/
static __always_inline bool should_resched(int preempt_offset)
{
return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
return unlikely(raw_cpu_read_4(pcpu_hot.preempt_count) == preempt_offset);
}
#ifdef CONFIG_PREEMPTION

8
arch/x86/kernel/cpu/common.c
View File

@ -2014,6 +2014,7 @@ __setup("clearcpuid=", setup_clearcpuid);
DEFINE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot) = {
.current_task = &init_task,
.preempt_count = INIT_PREEMPT_COUNT,
};
EXPORT_PER_CPU_SYMBOL(pcpu_hot);
@ -2022,13 +2023,9 @@ DEFINE_PER_CPU_FIRST(struct fixed_percpu_data,
fixed_percpu_data) __aligned(PAGE_SIZE) __visible;
EXPORT_PER_CPU_SYMBOL_GPL(fixed_percpu_data);
DEFINE_PER_CPU(void *, hardirq_stack_ptr);
DEFINE_PER_CPU(bool, hardirq_stack_inuse);
DEFINE_PER_CPU(int, __preempt_count) = INIT_PREEMPT_COUNT;
EXPORT_PER_CPU_SYMBOL(__preempt_count);
DEFINE_PER_CPU(unsigned long, cpu_current_top_of_stack) = TOP_OF_INIT_STACK;
static void wrmsrl_cstar(unsigned long val)
@ -2081,9 +2078,6 @@ void syscall_init(void)
#else /* CONFIG_X86_64 */
DEFINE_PER_CPU(int, __preempt_count) = INIT_PREEMPT_COUNT;
EXPORT_PER_CPU_SYMBOL(__preempt_count);
/*
* On x86_32, vm86 modifies tss.sp0, so sp0 isn't a reliable way to find
* the top of the kernel stack. Use an extra percpu variable to track the