remove sched notifier for cross-cpu migrations (e04c5d76) · Commits · 戴 / test

arch/x86/include/asm/pvclock.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -93,7 +93,6 @@ unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,

		struct pvclock_vsyscall_time_info {
		struct pvclock_vcpu_time_info pvti;
		u32 migrate_count;
		} __attribute__((__aligned__(SMP_CACHE_BYTES)));

		#define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)

arch/x86/kernel/pvclock.c

+0 −44

Original line number	Diff line number	Diff line
		@@ -128,46 +128,7 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock,
		set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
		}

		static struct pvclock_vsyscall_time_info *pvclock_vdso_info;

		static struct pvclock_vsyscall_time_info *
		pvclock_get_vsyscall_user_time_info(int cpu)
		{
		if (!pvclock_vdso_info) {
		BUG();
		return NULL;
		}

		return &pvclock_vdso_info[cpu];
		}

		struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu)
		{
		return &pvclock_get_vsyscall_user_time_info(cpu)->pvti;
		}

		#ifdef CONFIG_X86_64
		static int pvclock_task_migrate(struct notifier_block *nb, unsigned long l,
		void *v)
		{
		struct task_migration_notifier *mn = v;
		struct pvclock_vsyscall_time_info *pvti;

		pvti = pvclock_get_vsyscall_user_time_info(mn->from_cpu);

		/* this is NULL when pvclock vsyscall is not initialized */
		if (unlikely(pvti == NULL))
		return NOTIFY_DONE;

		pvti->migrate_count++;

		return NOTIFY_DONE;
		}

		static struct notifier_block pvclock_migrate = {
		.notifier_call = pvclock_task_migrate,
		};

		/*
		* Initialize the generic pvclock vsyscall state. This will allocate
		* a/some page(s) for the per-vcpu pvclock information, set up a
		@@ -181,17 +142,12 @@ int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i,

		WARN_ON (size != PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE);

		pvclock_vdso_info = i;

		for (idx = 0; idx <= (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {
		__set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,
		__pa(i) + (idx*PAGE_SIZE),
		PAGE_KERNEL_VVAR);
		}


		register_task_migration_notifier(&pvclock_migrate);

		return 0;
		}
		#endif

arch/x86/vdso/vclock_gettime.c

+8 −8

Original line number	Diff line number	Diff line
		@@ -85,15 +85,18 @@ static notrace cycle_t vread_pvclock(int *mode)
		cycle_t ret;
		u64 last;
		u32 version;
		u32 migrate_count;
		u8 flags;
		unsigned cpu, cpu1;


		/*
		* When looping to get a consistent (time-info, tsc) pair, we
		* also need to deal with the possibility we can switch vcpus,
		* so make sure we always re-fetch time-info for the current vcpu.
		* Note: hypervisor must guarantee that:
		* 1. cpu ID number maps 1:1 to per-CPU pvclock time info.
		* 2. that per-CPU pvclock time info is updated if the
		* underlying CPU changes.
		* 3. that version is increased whenever underlying CPU
		* changes.
		*
		*/
		do {
		cpu = __getcpu() & VGETCPU_CPU_MASK;
		@@ -104,8 +107,6 @@ static notrace cycle_t vread_pvclock(int *mode)

		pvti = get_pvti(cpu);

		migrate_count = pvti->migrate_count;

		version = __pvclock_read_cycles(&pvti->pvti, &ret, &flags);

		/*
		@@ -117,8 +118,7 @@ static notrace cycle_t vread_pvclock(int *mode)
		cpu1 = __getcpu() & VGETCPU_CPU_MASK;
		} while (unlikely(cpu != cpu1 \|\|
		(pvti->pvti.version & 1) \|\|
		pvti->pvti.version != version \|\|
		pvti->migrate_count != migrate_count));
		pvti->pvti.version != version));

		if (unlikely(!(flags & PVCLOCK_TSC_STABLE_BIT)))
		*mode = VCLOCK_NONE;

include/linux/sched.h

+0 −8

Original line number	Diff line number	Diff line
		@@ -107,14 +107,6 @@ extern unsigned long this_cpu_load(void);
		extern void calc_global_load(unsigned long ticks);
		extern void update_cpu_load_nohz(void);

		/* Notifier for when a task gets migrated to a new CPU */
		struct task_migration_notifier {
		struct task_struct *task;
		int from_cpu;
		int to_cpu;
		};
		extern void register_task_migration_notifier(struct notifier_block *n);

		extern unsigned long get_parent_ip(unsigned long addr);

		extern void dump_cpu_task(int cpu);

kernel/sched/core.c

+0 −15

Original line number	Diff line number	Diff line
		@@ -976,13 +976,6 @@ void check_preempt_curr(struct rq rq, struct task_struct p, int flags)
		rq->skip_clock_update = 1;
		}

		static ATOMIC_NOTIFIER_HEAD(task_migration_notifier);

		void register_task_migration_notifier(struct notifier_block *n)
		{
		atomic_notifier_chain_register(&task_migration_notifier, n);
		}

		#ifdef CONFIG_SMP
		void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
		{
		@@ -1013,18 +1006,10 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
		trace_sched_migrate_task(p, new_cpu);

		if (task_cpu(p) != new_cpu) {
		struct task_migration_notifier tmn;

		if (p->sched_class->migrate_task_rq)
		p->sched_class->migrate_task_rq(p, new_cpu);
		p->se.nr_migrations++;
		perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);

		tmn.task = p;
		tmn.from_cpu = task_cpu(p);
		tmn.to_cpu = new_cpu;

		atomic_notifier_call_chain(&task_migration_notifier, 0, &tmn);
		}

		__set_task_cpu(p, new_cpu);

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