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authorRobert Richter <rric@kernel.org>2013-02-06 21:26:24 +0400
committerIngo Molnar <mingo@kernel.org>2013-02-06 22:45:22 +0400
commit2c53c3dd0b6497484b29fd49d34ef98acbc14577 (patch)
tree6aae3a8a73292f0a024cbd78de68ad7b0498d3b5 /arch
parentf2b4367a69c60c644a1df36f63a65e0e677d3b0f (diff)
downloadlinux-2c53c3dd0b6497484b29fd49d34ef98acbc14577.tar.xz
perf/x86/amd: Rework northbridge event constraints handler
Code simplification. No functional changes. Signed-off-by: Robert Richter <rric@kernel.org> Signed-off-by: Jacob Shin <jacob.shin@amd.com> Acked-by: Stephane Eranian <eranian@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Robert Richter <rric@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1360171589-6381-2-git-send-email-jacob.shin@amd.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/perf_event_amd.c68
1 files changed, 26 insertions, 42 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
index c93bc4e813a0..e7963c7af683 100644
--- a/arch/x86/kernel/cpu/perf_event_amd.c
+++ b/arch/x86/kernel/cpu/perf_event_amd.c
@@ -256,9 +256,8 @@ amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
struct amd_nb *nb = cpuc->amd_nb;
- struct perf_event *old = NULL;
- int max = x86_pmu.num_counters;
- int i, j, k = -1;
+ struct perf_event *old;
+ int idx, new = -1;
/*
* if not NB event or no NB, then no constraints
@@ -276,48 +275,33 @@ amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
* because of successive calls to x86_schedule_events() from
* hw_perf_group_sched_in() without hw_perf_enable()
*/
- for (i = 0; i < max; i++) {
- /*
- * keep track of first free slot
- */
- if (k == -1 && !nb->owners[i])
- k = i;
+ for (idx = 0; idx < x86_pmu.num_counters; idx++) {
+ if (new == -1 || hwc->idx == idx)
+ /* assign free slot, prefer hwc->idx */
+ old = cmpxchg(nb->owners + idx, NULL, event);
+ else if (nb->owners[idx] == event)
+ /* event already present */
+ old = event;
+ else
+ continue;
+
+ if (old && old != event)
+ continue;
+
+ /* reassign to this slot */
+ if (new != -1)
+ cmpxchg(nb->owners + new, event, NULL);
+ new = idx;
/* already present, reuse */
- if (nb->owners[i] == event)
- goto done;
- }
- /*
- * not present, so grab a new slot
- * starting either at:
- */
- if (hwc->idx != -1) {
- /* previous assignment */
- i = hwc->idx;
- } else if (k != -1) {
- /* start from free slot found */
- i = k;
- } else {
- /*
- * event not found, no slot found in
- * first pass, try again from the
- * beginning
- */
- i = 0;
- }
- j = i;
- do {
- old = cmpxchg(nb->owners+i, NULL, event);
- if (!old)
+ if (old == event)
break;
- if (++i == max)
- i = 0;
- } while (i != j);
-done:
- if (!old)
- return &nb->event_constraints[i];
-
- return &emptyconstraint;
+ }
+
+ if (new == -1)
+ return &emptyconstraint;
+
+ return &nb->event_constraints[new];
}
static struct amd_nb *amd_alloc_nb(int cpu)