From c9601247f8f3fdc18aed7ed7e490e8dfcd07f122 Mon Sep 17 00:00:00 2001 From: Vince Weaver Date: Fri, 2 Aug 2013 10:47:34 -0400 Subject: [PATCH] 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@c560-003.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 Signed-off-by: Vince Weaver Cc: zheng.z.yan@intel.com Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Paul Mackerras Cc: Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1308021037280.26119@vincent-weaver-1.um.maine.edu Signed-off-by: Ingo Molnar --- 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 cad791dbde95..1fb6c72717bd 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 */ }, }; -- 2.20.1