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perf: Provide a separate task context for swevents

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Since software events are always schedulable, mixing them up with
hardware events (who are not) can lead to funny scheduling oddities.

Giving them their own context solves this.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-09-07 17:34:50 +02:00 committed by Ingo Molnar
parent 8dc85d5472
commit 89a1e18731
4 changed files with 33 additions and 19 deletions
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9
include/linux/perf_event.h
View File

@ -952,14 +952,7 @@ extern int perf_event_overflow(struct perf_event *event, int nmi,
*/
static inline int is_software_event(struct perf_event *event)
{
switch (event->attr.type) {
case PERF_TYPE_SOFTWARE:
case PERF_TYPE_TRACEPOINT:
/* for now the breakpoint stuff also works as software event */
case PERF_TYPE_BREAKPOINT:
return 1;
}
return 0;
return event->pmu->task_ctx_nr == perf_sw_context;
}
extern atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];

1
include/linux/sched.h
View File

@ -1163,6 +1163,7 @@ struct rcu_node;
enum perf_event_task_context {
perf_invalid_context = -1,
perf_hw_context = 0,
perf_sw_context,
perf_nr_task_contexts,
};

2
kernel/hw_breakpoint.c
View File

@ -610,6 +610,8 @@ static void hw_breakpoint_stop(struct perf_event *bp, int flags)
}
static struct pmu perf_breakpoint = {
.task_ctx_nr = perf_sw_context, /* could eventually get its own */
.event_init = hw_breakpoint_event_init,
.add = hw_breakpoint_add,
.del = hw_breakpoint_del,

40
kernel/perf_event.c
View File

@ -4709,6 +4709,8 @@ static int perf_swevent_init(struct perf_event *event)
}
static struct pmu perf_swevent = {
.task_ctx_nr = perf_sw_context,
.event_init = perf_swevent_init,
.add = perf_swevent_add,
.del = perf_swevent_del,
@ -4800,6 +4802,8 @@ static int perf_tp_event_init(struct perf_event *event)
}
static struct pmu perf_tracepoint = {
.task_ctx_nr = perf_sw_context,
.event_init = perf_tp_event_init,
.add = perf_trace_add,
.del = perf_trace_del,
@ -4988,6 +4992,8 @@ static int cpu_clock_event_init(struct perf_event *event)
}
static struct pmu perf_cpu_clock = {
.task_ctx_nr = perf_sw_context,
.event_init = cpu_clock_event_init,
.add = cpu_clock_event_add,
.del = cpu_clock_event_del,
@ -5063,6 +5069,8 @@ static int task_clock_event_init(struct perf_event *event)
}
static struct pmu perf_task_clock = {
.task_ctx_nr = perf_sw_context,
.event_init = task_clock_event_init,
.add = task_clock_event_add,
.del = task_clock_event_del,
@ -5490,6 +5498,7 @@ SYSCALL_DEFINE5(perf_event_open,
struct perf_event_context *ctx;
struct file *event_file = NULL;
struct file *group_file = NULL;
struct pmu *pmu;
int event_fd;
int fput_needed = 0;
int err;
@ -5522,20 +5531,11 @@ SYSCALL_DEFINE5(perf_event_open,
goto err_fd;
}
/*
* Get the target context (task or percpu):
*/
ctx = find_get_context(event->pmu, pid, cpu);
if (IS_ERR(ctx)) {
err = PTR_ERR(ctx);
goto err_alloc;
}
if (group_fd != -1) {
group_leader = perf_fget_light(group_fd, &fput_needed);
if (IS_ERR(group_leader)) {
err = PTR_ERR(group_leader);
goto err_context;
goto err_alloc;
}
group_file = group_leader->filp;
if (flags & PERF_FLAG_FD_OUTPUT)
@ -5544,6 +5544,23 @@ SYSCALL_DEFINE5(perf_event_open,
group_leader = NULL;
}
/*
* Special case software events and allow them to be part of
* any hardware group.
*/
pmu = event->pmu;
if ((pmu->task_ctx_nr == perf_sw_context) && group_leader)
pmu = group_leader->pmu;
/*
* Get the target context (task or percpu):
*/
ctx = find_get_context(pmu, pid, cpu);
if (IS_ERR(ctx)) {
err = PTR_ERR(ctx);
goto err_group_fd;
}
/*
* Look up the group leader (we will attach this event to it):
*/
@ -5605,8 +5622,9 @@ SYSCALL_DEFINE5(perf_event_open,
return event_fd;
err_context:
fput_light(group_file, fput_needed);
put_ctx(ctx);
err_group_fd:
fput_light(group_file, fput_needed);
err_alloc:
free_event(event);
err_fd: