perf: Provide a separate task context for swevents
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>
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 6f15009..3b2aaff 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -610,6 +610,8 @@
}
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,
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 7223ea8..357ee8d 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4709,6 +4709,8 @@
}
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 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 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 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 @@
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 @@
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)
@@ -5545,6 +5545,23 @@
}
/*
+ * 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):
*/
if (group_leader) {
@@ -5605,8 +5622,9 @@
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:
