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perf: Add pmu specific data for perf task context

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Introduce a new flag PERF_ATTACH_TASK_DATA for perf event's attach
stata. The flag is set by PMU's event_init() callback, it indicates
that perf event needs PMU specific data.

The PMU specific data are initialized to zeros. Later patches will
use PMU specific data to save LBR stack.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: eranian@google.com
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1415156173-10035-6-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Yan, Zheng 2014-11-04 21:56:01 -05:00 committed by Ingo Molnar
parent e9d7f7cd97
commit 4af57ef28c
2 changed files with 42 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/perf_event.h
View File

@ -271,6 +271,10 @@ struct pmu {
*/
void (*sched_task) (struct perf_event_context *ctx,
bool sched_in);
/*
* PMU specific data size
*/
size_t task_ctx_size;
};
@ -307,6 +311,7 @@ struct swevent_hlist {
#define PERF_ATTACH_CONTEXT 0x01
#define PERF_ATTACH_GROUP 0x02
#define PERF_ATTACH_TASK 0x04
#define PERF_ATTACH_TASK_DATA 0x08
struct perf_cgroup;
struct ring_buffer;
@ -511,6 +516,7 @@ struct perf_event_context {
u64 generation;
int pin_count;
int nr_cgroups; /* cgroup evts */
void *task_ctx_data; /* pmu specific data */
struct rcu_head rcu_head;
struct delayed_work orphans_remove;

40
kernel/events/core.c
View File

@ -905,6 +905,15 @@ static void get_ctx(struct perf_event_context *ctx)
WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
}
static void free_ctx(struct rcu_head *head)
{
struct perf_event_context *ctx;
ctx = container_of(head, struct perf_event_context, rcu_head);
kfree(ctx->task_ctx_data);
kfree(ctx);
}
static void put_ctx(struct perf_event_context *ctx)
{
if (atomic_dec_and_test(&ctx->refcount)) {
@ -912,7 +921,7 @@ static void put_ctx(struct perf_event_context *ctx)
put_ctx(ctx->parent_ctx);
if (ctx->task)
put_task_struct(ctx->task);
kfree_rcu(ctx, rcu_head);
call_rcu(&ctx->rcu_head, free_ctx);
}
}
@ -3309,12 +3318,15 @@ errout:
* Returns a matching context with refcount and pincount.
*/
static struct perf_event_context *
find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)
find_get_context(struct pmu *pmu, struct task_struct *task,
struct perf_event *event)
{
struct perf_event_context *ctx, *clone_ctx = NULL;
struct perf_cpu_context *cpuctx;
void *task_ctx_data = NULL;
unsigned long flags;
int ctxn, err;
int cpu = event->cpu;
if (!task) {
/* Must be root to operate on a CPU event: */
@ -3342,11 +3354,24 @@ find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)
if (ctxn < 0)
goto errout;
if (event->attach_state & PERF_ATTACH_TASK_DATA) {
task_ctx_data = kzalloc(pmu->task_ctx_size, GFP_KERNEL);
if (!task_ctx_data) {
err = -ENOMEM;
goto errout;
}
}
retry:
ctx = perf_lock_task_context(task, ctxn, &flags);
if (ctx) {
clone_ctx = unclone_ctx(ctx);
++ctx->pin_count;
if (task_ctx_data && !ctx->task_ctx_data) {
ctx->task_ctx_data = task_ctx_data;
task_ctx_data = NULL;
}
raw_spin_unlock_irqrestore(&ctx->lock, flags);
if (clone_ctx)
@ -3357,6 +3382,11 @@ retry:
if (!ctx)
goto errout;
if (task_ctx_data) {
ctx->task_ctx_data = task_ctx_data;
task_ctx_data = NULL;
}
err = 0;
mutex_lock(&task->perf_event_mutex);
/*
@ -3383,9 +3413,11 @@ retry:
}
}
kfree(task_ctx_data);
return ctx;
errout:
kfree(task_ctx_data);
return ERR_PTR(err);
}
@ -7559,7 +7591,7 @@ SYSCALL_DEFINE5(perf_event_open,
/*
* Get the target context (task or percpu):
*/
ctx = find_get_context(pmu, task, event->cpu);
ctx = find_get_context(pmu, task, event);
if (IS_ERR(ctx)) {
err = PTR_ERR(ctx);
goto err_alloc;
@ -7765,7 +7797,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
account_event(event);
ctx = find_get_context(event->pmu, task, cpu);
ctx = find_get_context(event->pmu, task, event);
if (IS_ERR(ctx)) {
err = PTR_ERR(ctx);
goto err_free;