From: Jacob Shin <jacob.shin@amd.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Stephane Eranian <eranian@google.com>,
Robert Richter <rric@kernel.org>, <x86@kernel.org>,
<linux-kernel@vger.kernel.org>, Jacob Shin <jacob.shin@amd.com>
Subject: [PATCH 1/4] perf, amd: Simplify northbridge event constraints handler
Date: Fri, 9 Nov 2012 19:01:35 -0600 [thread overview]
Message-ID: <1352509298-7319-2-git-send-email-jacob.shin@amd.com> (raw)
In-Reply-To: <1352509298-7319-1-git-send-email-jacob.shin@amd.com>
From: Robert Richter <rric@kernel.org>
Code simplification, there is no functional change.
Signed-off-by: Robert Richter <rric@kernel.org>
Signed-off-by: Jacob Shin <jacob.shin@amd.com>
---
arch/x86/kernel/cpu/perf_event_amd.c | 68 +++++++++++++---------------------
1 file 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 4528ae7..d60c5c7 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)
--
1.7.9.5
next prev parent reply other threads:[~2012-11-10 1:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-10 1:01 [PATCH 0/4] perf, amd: Enable AMD family 15h northbridge counters Jacob Shin
2012-11-10 1:01 ` Jacob Shin [this message]
2012-11-10 1:01 ` [PATCH 2/4] perf, amd: Refactor northbridge event constraints handler for code sharing Jacob Shin
2012-11-10 1:01 ` [PATCH 3/4] perf, x86: Move MSR address offset calculation to architecture specific files Jacob Shin
2012-11-10 1:01 ` [PATCH 4/4] perf, amd: Enable northbridge performance counters on AMD family 15h Jacob Shin
2012-11-10 11:50 ` [PATCH 0/4] perf, amd: Enable AMD family 15h northbridge counters Robert Richter
2012-11-11 18:17 ` Stephane Eranian
2012-11-12 14:36 ` Robert Richter
2012-11-11 18:44 ` Jacob Shin
2012-11-12 12:24 ` Stephane Eranian
2012-11-12 14:22 ` Robert Richter
2012-11-12 16:13 ` Jacob Shin
2012-11-12 21:08 ` Stephane Eranian
2012-11-12 14:55 ` Robert Richter
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