Commit 4b9cf23c authored by Ionela Voinescu's avatar Ionela Voinescu Committed by Catalin Marinas
Browse files

arm64: wrap and generalise counter read functions 



In preparation for other uses of Activity Monitors (AMU) cycle counters,
place counter read functionality in generic functions that can reused:
read_corecnt() and read_constcnt().

As a result, implement update_freq_counters_refs() to replace
init_cpu_freq_invariance_counters() and both initialise and update
the per-cpu reference variables.

Signed-off-by: default avatarIonela Voinescu <ionela.voinescu@arm.com>
Reviewed-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201106125334.21570-2-ionela.voinescu@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent f8394f23

arch/arm64/include/asm/cpufeature.h

+5 −0
Original line number Diff line number Diff line
@@ -765,6 +765,11 @@ static inline bool cpu_has_hw_af(void) 
#ifdef CONFIG_ARM64_AMU_EXTN

/* Check whether the cpu supports the Activity Monitors Unit (AMU) */

extern bool cpu_has_amu_feat(int cpu);

#else

static inline bool cpu_has_amu_feat(int cpu)

{

	return false;

}

#endif



static inline unsigned int get_vmid_bits(u64 mmfr1)

arch/arm64/include/asm/topology.h

+3 −1
Original line number Diff line number Diff line
@@ -16,12 +16,14 @@ int pcibus_to_node(struct pci_bus *bus); 


#include <linux/arch_topology.h>



void update_freq_counters_refs(void);

void topology_scale_freq_tick(void);



#ifdef CONFIG_ARM64_AMU_EXTN

/*

 * Replace task scheduler's default counter-based

 * frequency-invariance scale factor setting.

 */

void topology_scale_freq_tick(void);

#define arch_scale_freq_tick topology_scale_freq_tick

#endif /* CONFIG_ARM64_AMU_EXTN */

arch/arm64/kernel/cpufeature.c

+1 −4
Original line number Diff line number Diff line
@@ -1526,16 +1526,13 @@ bool cpu_has_amu_feat(int cpu) 
	return cpumask_test_cpu(cpu, &amu_cpus);

}



/* Initialize the use of AMU counters for frequency invariance */

extern void init_cpu_freq_invariance_counters(void);



static void cpu_amu_enable(struct arm64_cpu_capabilities const *cap)

{

	if (has_cpuid_feature(cap, SCOPE_LOCAL_CPU)) {

		pr_info("detected CPU%d: Activity Monitors Unit (AMU)\n",

			smp_processor_id());

		cpumask_set_cpu(smp_processor_id(), &amu_cpus);

		init_cpu_freq_invariance_counters();

		update_freq_counters_refs();

	}

}

arch/arm64/kernel/topology.c

+14 −9
Original line number Diff line number Diff line
@@ -124,6 +124,12 @@ int __init parse_acpi_topology(void) 
#endif



#ifdef CONFIG_ARM64_AMU_EXTN

#define read_corecnt()	read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0)

#define read_constcnt()	read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0)

#else

#define read_corecnt()	(0UL)

#define read_constcnt()	(0UL)

#endif



#undef pr_fmt

#define pr_fmt(fmt) "AMU: " fmt
@@ -133,13 +139,10 @@ static DEFINE_PER_CPU(u64, arch_const_cycles_prev); 
static DEFINE_PER_CPU(u64, arch_core_cycles_prev);

static cpumask_var_t amu_fie_cpus;



/* Initialize counter reference per-cpu variables for the current CPU */

void init_cpu_freq_invariance_counters(void)

void update_freq_counters_refs(void)

{

	this_cpu_write(arch_core_cycles_prev,

		       read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0));

	this_cpu_write(arch_const_cycles_prev,

		       read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0));

	this_cpu_write(arch_core_cycles_prev, read_corecnt());

	this_cpu_write(arch_const_cycles_prev, read_constcnt());

}



static int validate_cpu_freq_invariance_counters(int cpu)
@@ -280,11 +283,14 @@ void topology_scale_freq_tick(void) 
	if (!cpumask_test_cpu(cpu, amu_fie_cpus))

		return;



	const_cnt = read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0);

	core_cnt = read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0);

	prev_const_cnt = this_cpu_read(arch_const_cycles_prev);

	prev_core_cnt = this_cpu_read(arch_core_cycles_prev);



	update_freq_counters_refs();



	const_cnt = this_cpu_read(arch_const_cycles_prev);

	core_cnt = this_cpu_read(arch_core_cycles_prev);



	if (unlikely(core_cnt <= prev_core_cnt ||

		     const_cnt <= prev_const_cnt))

		goto store_and_exit;
@@ -309,4 +315,3 @@ void topology_scale_freq_tick(void) 
	this_cpu_write(arch_core_cycles_prev, core_cnt);

	this_cpu_write(arch_const_cycles_prev, const_cnt);

}
 
#endif /* CONFIG_ARM64_AMU_EXTN */