Commit ab0cce56 authored by Jiri Olsa's avatar Jiri Olsa Committed by Ingo Molnar

Revert "sched, perf: Use a single callback into the scheduler"

This reverts commit cb04ff9a ("sched, perf: Use a single
callback into the scheduler").

Before this change was introduced, the process switch worked
like this (wrt. to perf event schedule):

     schedule (prev, next)
       - schedule out all perf events for prev
       - switch to next
       - schedule in all perf events for current (next)

After the commit, the process switch looks like:

     schedule (prev, next)
       - schedule out all perf events for prev
       - schedule in all perf events for (next)
       - switch to next

The problem is, that after we schedule perf events in, the pmu
is enabled and we can receive events even before we make the
switch to next - so "current" still being prev process (event
SAMPLE data are filled based on the value of the "current"
process).

Thats exactly what we see for test__PERF_RECORD test. We receive
SAMPLES with PID of the process that our tracee is scheduled
from.

Discussed with Peter Zijlstra:

 > Bah!, yeah I guess reverting is the right thing for now. Sad
 > though.
 >
 > So by having the two hooks we have a black-spot between them
 > where we receive no events at all, this black-spot covers the
 > hand-over of current and we thus don't receive the 'wrong'
 > events.
 >
 > I rather liked we could do away with both that black-spot and
 > clean up the code a little, but apparently people rely on it.
Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: acme@redhat.com
Cc: paulus@samba.org
Cc: cjashfor@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/20120523111302.GC1638@m.brq.redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 26252ea6
...@@ -1084,8 +1084,10 @@ extern void perf_pmu_unregister(struct pmu *pmu); ...@@ -1084,8 +1084,10 @@ extern void perf_pmu_unregister(struct pmu *pmu);
extern int perf_num_counters(void); extern int perf_num_counters(void);
extern const char *perf_pmu_name(void); extern const char *perf_pmu_name(void);
extern void __perf_event_task_sched(struct task_struct *prev, extern void __perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *next); struct task_struct *task);
extern void __perf_event_task_sched_out(struct task_struct *prev,
struct task_struct *next);
extern int perf_event_init_task(struct task_struct *child); extern int perf_event_init_task(struct task_struct *child);
extern void perf_event_exit_task(struct task_struct *child); extern void perf_event_exit_task(struct task_struct *child);
extern void perf_event_free_task(struct task_struct *task); extern void perf_event_free_task(struct task_struct *task);
...@@ -1205,13 +1207,20 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr) ...@@ -1205,13 +1207,20 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
extern struct static_key_deferred perf_sched_events; extern struct static_key_deferred perf_sched_events;
static inline void perf_event_task_sched(struct task_struct *prev, static inline void perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *task) struct task_struct *task)
{
if (static_key_false(&perf_sched_events.key))
__perf_event_task_sched_in(prev, task);
}
static inline void perf_event_task_sched_out(struct task_struct *prev,
struct task_struct *next)
{ {
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, NULL, 0); perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, NULL, 0);
if (static_key_false(&perf_sched_events.key)) if (static_key_false(&perf_sched_events.key))
__perf_event_task_sched(prev, task); __perf_event_task_sched_out(prev, next);
} }
extern void perf_event_mmap(struct vm_area_struct *vma); extern void perf_event_mmap(struct vm_area_struct *vma);
...@@ -1286,8 +1295,11 @@ extern void perf_event_disable(struct perf_event *event); ...@@ -1286,8 +1295,11 @@ extern void perf_event_disable(struct perf_event *event);
extern void perf_event_task_tick(void); extern void perf_event_task_tick(void);
#else #else
static inline void static inline void
perf_event_task_sched(struct task_struct *prev, perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *task) { } struct task_struct *task) { }
static inline void
perf_event_task_sched_out(struct task_struct *prev,
struct task_struct *next) { }
static inline int perf_event_init_task(struct task_struct *child) { return 0; } static inline int perf_event_init_task(struct task_struct *child) { return 0; }
static inline void perf_event_exit_task(struct task_struct *child) { } static inline void perf_event_exit_task(struct task_struct *child) { }
static inline void perf_event_free_task(struct task_struct *task) { } static inline void perf_event_free_task(struct task_struct *task) { }
......
...@@ -2039,8 +2039,8 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, ...@@ -2039,8 +2039,8 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
* accessing the event control register. If a NMI hits, then it will * accessing the event control register. If a NMI hits, then it will
* not restart the event. * not restart the event.
*/ */
static void __perf_event_task_sched_out(struct task_struct *task, void __perf_event_task_sched_out(struct task_struct *task,
struct task_struct *next) struct task_struct *next)
{ {
int ctxn; int ctxn;
...@@ -2279,8 +2279,8 @@ static void perf_branch_stack_sched_in(struct task_struct *prev, ...@@ -2279,8 +2279,8 @@ static void perf_branch_stack_sched_in(struct task_struct *prev,
* accessing the event control register. If a NMI hits, then it will * accessing the event control register. If a NMI hits, then it will
* keep the event running. * keep the event running.
*/ */
static void __perf_event_task_sched_in(struct task_struct *prev, void __perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *task) struct task_struct *task)
{ {
struct perf_event_context *ctx; struct perf_event_context *ctx;
int ctxn; int ctxn;
...@@ -2305,12 +2305,6 @@ static void __perf_event_task_sched_in(struct task_struct *prev, ...@@ -2305,12 +2305,6 @@ static void __perf_event_task_sched_in(struct task_struct *prev,
perf_branch_stack_sched_in(prev, task); perf_branch_stack_sched_in(prev, task);
} }
void __perf_event_task_sched(struct task_struct *prev, struct task_struct *next)
{
__perf_event_task_sched_out(prev, next);
__perf_event_task_sched_in(prev, next);
}
static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count) static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
{ {
u64 frequency = event->attr.sample_freq; u64 frequency = event->attr.sample_freq;
......
...@@ -1913,7 +1913,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, ...@@ -1913,7 +1913,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next) struct task_struct *next)
{ {
sched_info_switch(prev, next); sched_info_switch(prev, next);
perf_event_task_sched(prev, next); perf_event_task_sched_out(prev, next);
fire_sched_out_preempt_notifiers(prev, next); fire_sched_out_preempt_notifiers(prev, next);
prepare_lock_switch(rq, next); prepare_lock_switch(rq, next);
prepare_arch_switch(next); prepare_arch_switch(next);
...@@ -1956,6 +1956,13 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev) ...@@ -1956,6 +1956,13 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
*/ */
prev_state = prev->state; prev_state = prev->state;
finish_arch_switch(prev); finish_arch_switch(prev);
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
local_irq_disable();
#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
perf_event_task_sched_in(prev, current);
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
local_irq_enable();
#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
finish_lock_switch(rq, prev); finish_lock_switch(rq, prev);
finish_arch_post_lock_switch(); finish_arch_post_lock_switch();
......
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