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perf, x86: bug fix for cycles:p and cycles:pp on SLM

PATCH New [email protected] 2 participants 2 messages Jan 12, 2015 – Jan 16, 2015

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PATCH v2 1/1 perf, x86: bug fix for cycles:p and cycles:pp on SLM

From: Kan Liang <[email protected]>

cycles:p and cycles:pp do not work on SLM since 86a04461a99f ("perf/x86: Revamp PEBS event selection")

UOPS_RETIRED.ALL is not a PEBS capable event, so it should not be used to count cycle number.
Actually SLM call intel_pebs_aliases_core2 which uses INST_RETIRED.ANY_P counts the number of cycles. It's a PEBS capable event. But inv and cmask must be set to count cycles.
Considering SLM allows all events as PEBS with no flags, here only INST_RETIRED.ANY_P, inv=1, cmask=16 need to specially handled.

Signed-off-by Kan Liang <[email protected]>

---
Changes since V1
- Only handle INST_RETIRED.ANY_P, inv=1, cmask=16

 arch/x86/kernel/cpu/perf_event_intel_ds.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
arch/x86/kernel/cpu/perf_event_intel_ds.c +2 -2
index 3c895d4..0739833 100644
@@ -568,8 +568,8 @@ struct event_constraint intel_atom_pebs_event_constraints[] = {
 };
 
 struct event_constraint intel_slm_pebs_event_constraints[] = {
-	/* UOPS_RETIRED.ALL, inv=1, cmask=16 (cycles:p). */
-	INTEL_FLAGS_EVENT_CONSTRAINT(0x108001c2, 0xf),
+	/* INST_RETIRED.ANY_P, inv=1, cmask=16 (cycles:p). */
+	INTEL_FLAGS_EVENT_CONSTRAINT(0x108000c0, 0x1),
 	/* Allow all events as PEBS with no flags */
 	INTEL_ALL_EVENT_CONSTRAINT(0, 0x1),
 	EVENT_CONSTRAINT_END
Signature · 1 line
1.7.11.7
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[tip:perf/urgent] perf/x86/intel: Fix bug for "cycles:p" and " cycles:pp" on SLM

perf/x86/intel: Fix bug for "cycles:p" and "cycles:pp" on SLM
Commit-ID:  33636732dcd7cc738a5913bb730d663c6b03c8fb
Gitweb:     http://git.kernel.org/tip/33636732dcd7cc738a5913bb730d663c6b03c8fb
Author:     Kan Liang <[email protected]>
AuthorDate: Mon, 12 Jan 2015 17:42:21 +0000
Committer:  Ingo Molnar <[email protected]>
CommitDate: Fri, 16 Jan 2015 09:06:59 +0100

perf/x86/intel: Fix bug for "cycles:p" and "cycles:pp" on SLM

cycles:p and cycles:pp do not work on SLM since commit:

86a04461a99f ("perf/x86: Revamp PEBS event selection")

UOPS_RETIRED.ALL is not a PEBS capable event, so it should not be used to count cycle number.

Actually SLM calls intel_pebs_aliases_core2() which uses INST_RETIRED.ANY_P to count the number of cycles. It's a PEBS capable event. But inv and cmask must be set to count cycles.

Considering SLM allows all events as PEBS with no flags, only INST_RETIRED.ANY_P, inv=1, cmask=16 needs to handled specially.

Signed-off-by Kan Liang <[email protected]>
Signed-off-by Peter Zijlstra (Intel) <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Cc Arnaldo Carvalho de Melo <[email protected]>
Cc Linus Torvalds <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
---
 arch/x86/kernel/cpu/perf_event_intel_ds.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
arch/x86/kernel/cpu/perf_event_intel_ds.c +2 -2
index 3c895d4..0739833 100644
@@ -568,8 +568,8 @@ struct event_constraint intel_atom_pebs_event_constraints[] = {
 };
 
 struct event_constraint intel_slm_pebs_event_constraints[] = {
-	/* UOPS_RETIRED.ALL, inv=1, cmask=16 (cycles:p). */
-	INTEL_FLAGS_EVENT_CONSTRAINT(0x108001c2, 0xf),
+	/* INST_RETIRED.ANY_P, inv=1, cmask=16 (cycles:p). */
+	INTEL_FLAGS_EVENT_CONSTRAINT(0x108000c0, 0x1),
 	/* Allow all events as PEBS with no flags */
 	INTEL_ALL_EVENT_CONSTRAINT(0, 0x1),
 	EVENT_CONSTRAINT_END