linux-kernel - [tip:perf/urgent] perf/x86: Fix intel QPI uncore event definitions

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Message-ID: <tip-c9601247f8f3fdc18aed7ed7e490e8dfcd07f122@git.kernel.org>
Date:	Mon, 5 Aug 2013 03:01:23 -0700
From:	tip-bot for Vince Weaver <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
	mingo@...nel.org, mccalpin@...c.utexas.edu,
	acme@...stprotocols.net, peterz@...radead.org,
	vincent.weaver@...ne.edu, stable@...nel.org, tglx@...utronix.de
Subject: [tip:perf/urgent] perf/x86:
  Fix intel QPI uncore event definitions

Commit-ID:  c9601247f8f3fdc18aed7ed7e490e8dfcd07f122
Gitweb:     http://git.kernel.org/tip/c9601247f8f3fdc18aed7ed7e490e8dfcd07f122
Author:     Vince Weaver <vincent.weaver@...ne.edu>
AuthorDate: Fri, 2 Aug 2013 10:47:34 -0400
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 5 Aug 2013 11:32:08 +0200

perf/x86: Fix intel QPI uncore event definitions

John McCalpin reports that the "drs_data" and "ncb_data" QPI
uncore events are missing the "extra bit" and always return zero
values unless the bit is properly set.

More details from him:

 According to the Xeon E5-2600 Product Family Uncore Performance
 Monitoring Guide, Table 2-94, about 1/2 of the QPI Link Layer events
 (including the ones that "perf" calls "drs_data" and "ncb_data") require
 that the "extra bit" be set.

 This was confusing for a while -- a note at the bottom of page 94 says
 that the "extra bit" is bit 16 of the control register.
 Unfortunately, Table 2-86 clearly says that bit 16 is reserved and must
 be zero.  Looking around a bit, I found that bit 21 appears to be the
 correct "extra bit", and further investigation shows that "perf" actually
 agrees with me:
	[root@...0-003.stampede]# cat /sys/bus/event_source/devices/uncore_qpi_0/format/event
	config:0-7,21

 So the command
	# perf -e "uncore_qpi_0/event=drs_data/"
 Is the same as
	# perf -e "uncore_qpi_0/event=0x02,umask=0x08/"
 While it should be
	# perf -e "uncore_qpi_0/event=0x102,umask=0x08/"

 I confirmed that this last version gives results that agree with the
 amount of data that I expected the STREAM benchmark to move across the QPI
 link in the second (cross-chip) test of the original script.

Reported-by: John McCalpin <mccalpin@...c.utexas.edu>
Signed-off-by: Vince Weaver <vincent.weaver@...ne.edu>
Cc: zheng.z.yan@...el.com
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: <stable@...nel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1308021037280.26119@vincent-weaver-1.um.maine.edu
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/perf_event_intel_uncore.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
index cad791d..1fb6c72 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -314,8 +314,8 @@ static struct uncore_event_desc snbep_uncore_imc_events[] = {
 static struct uncore_event_desc snbep_uncore_qpi_events[] = {
 	INTEL_UNCORE_EVENT_DESC(clockticks,       "event=0x14"),
 	INTEL_UNCORE_EVENT_DESC(txl_flits_active, "event=0x00,umask=0x06"),
-	INTEL_UNCORE_EVENT_DESC(drs_data,         "event=0x02,umask=0x08"),
-	INTEL_UNCORE_EVENT_DESC(ncb_data,         "event=0x03,umask=0x04"),
+	INTEL_UNCORE_EVENT_DESC(drs_data,         "event=0x102,umask=0x08"),
+	INTEL_UNCORE_EVENT_DESC(ncb_data,         "event=0x103,umask=0x04"),
 	{ /* end: all zeroes */ },
 };
 
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