Commit 3acfcefa authored by Li RongQing's avatar Li RongQing Committed by Ingo Molnar
Browse files

perf/x86/intel/bts: Allocate bts_ctx only if necessary 



Avoid unnecessary per-CPU memory allocation on unsupported CPUs,
this can save 12K memory for each CPU

Signed-off-by: default avatarLi RongQing <lirongqing@baidu.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Tested-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Acked-by: default avatarKan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20250122074103.3091-1-lirongqing@baidu.com
parent 8aeacf25

arch/x86/events/intel/bts.c

+13 −9
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ enum { 
	BTS_STATE_ACTIVE,

};



static DEFINE_PER_CPU(struct bts_ctx, bts_ctx);

static struct bts_ctx __percpu *bts_ctx;



#define BTS_RECORD_SIZE		24

#define BTS_SAFETY_MARGIN	4080
@@ -231,7 +231,7 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle); 


static void __bts_event_start(struct perf_event *event)

{

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);

	struct bts_buffer *buf = perf_get_aux(&bts->handle);

	u64 config = 0;
@@ -260,7 +260,7 @@ static void __bts_event_start(struct perf_event *event) 
static void bts_event_start(struct perf_event *event, int flags)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);

	struct bts_buffer *buf;



	buf = perf_aux_output_begin(&bts->handle, event);
@@ -290,7 +290,7 @@ static void bts_event_start(struct perf_event *event, int flags) 


static void __bts_event_stop(struct perf_event *event, int state)

{

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);



	/* ACTIVE -> INACTIVE(PMI)/STOPPED(->stop()) */

	WRITE_ONCE(bts->state, state);
@@ -305,7 +305,7 @@ static void __bts_event_stop(struct perf_event *event, int state) 
static void bts_event_stop(struct perf_event *event, int flags)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);

	struct bts_buffer *buf = NULL;

	int state = READ_ONCE(bts->state);
@@ -338,7 +338,7 @@ static void bts_event_stop(struct perf_event *event, int flags) 


void intel_bts_enable_local(void)

{

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);

	int state = READ_ONCE(bts->state);



	/*
@@ -358,7 +358,7 @@ void intel_bts_enable_local(void) 


void intel_bts_disable_local(void)

{

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);



	/*

	 * Here we transition from ACTIVE to INACTIVE;
@@ -450,7 +450,7 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle) 
int intel_bts_interrupt(void)

{

	struct debug_store *ds = this_cpu_ptr(&cpu_hw_events)->ds;

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);

	struct perf_event *event = bts->handle.event;

	struct bts_buffer *buf;

	s64 old_head;
@@ -518,7 +518,7 @@ static void bts_event_del(struct perf_event *event, int mode) 


static int bts_event_add(struct perf_event *event, int mode)

{

	struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);

	struct bts_ctx *bts = this_cpu_ptr(bts_ctx);

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	struct hw_perf_event *hwc = &event->hw;
@@ -605,6 +605,10 @@ static __init int bts_init(void) 
		return -ENODEV;

	}



	bts_ctx = alloc_percpu(struct bts_ctx);

	if (!bts_ctx)

		return -ENOMEM;



	bts_pmu.capabilities	= PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_ITRACE |

				  PERF_PMU_CAP_EXCLUSIVE;

	bts_pmu.task_ctx_nr	= perf_sw_context;