[PATCH] perf: Add a few generic stalled-cycles events
From: Sukadev Bhattiprolu
Date: Tue Sep 18 2012 - 13:59:01 EST
The existing generic event 'stalled-cycles-backend' corresponds to
PM_CMPLU_STALL event in Power7. While this event is useful, detailed
performance analysis often requires us to find more specific reasons
for the stalled cycle. For instance, stalled cycles in Power7 can
occur due to, among others:
- instruction fetch unit (IFU),
- Load-store-unit (LSU),
- Fixed point unit (FXU)
- Branch unit (BRU)
While it is possible to use raw codes to monitor these events, it quickly
becomes cumbersome with performance analysis frequently requiring mapping
the raw event codes in reports to their symbolic names.
This patch is a proposal to try and generalize such perf events. Since
the code changes are quite simple, I bunched all the 4 events together.
I am not familiar with how readily these events would map to other
architectures. Here is some information on the events for Power7:
stalled-cycles-fixed-point (PM_CMPLU_STALL_FXU)
Following a completion stall, the last instruction to finish
before completion resumes was from the Fixed Point Unit.
Completion stall is any period when no groups completed and
the completion table was not empty for that thread.
stalled-cycles-load-store (PM_CMPLU_STALL_LSU)
Following a completion stall, the last instruction to finish
before completion resumes was from the Load-Store Unit.
stalled-cycles-instruction-fetch (PM_CMPLU_STALL_IFU)
Following a completion stall, the last instruction to finish
before completion resumes was from the Instruction Fetch Unit.
stalled-cycles-branch (PM_CMPLU_STALL_BRU)
Following a completion stall, the last instruction to finish
before completion resumes was from the Branch Unit.
Looking for feedback on this approach and if this can be further extended.
Power7 has 530 events[2] out of which a "CPI stack analysis"[1] uses about 26
events.
[1] CPI Stack analysis
https://www.power.org/documentation/commonly-used-metrics-for-performance-analysis
[2] Power7 events:
https://www.power.org/documentation/comprehensive-pmu-event-reference-power7/
Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/perf/power7-pmu.c | 4 ++++
include/linux/perf_event.h | 4 ++++
tools/perf/builtin-stat.c | 4 ++++
tools/perf/util/evsel.c | 4 ++++
tools/perf/util/parse-events.l | 4 ++++
tools/perf/util/python.c | 4 ++++
6 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/perf/power7-pmu.c b/arch/powerpc/perf/power7-pmu.c
index 1251e4d..813e7c7 100644
--- a/arch/powerpc/perf/power7-pmu.c
+++ b/arch/powerpc/perf/power7-pmu.c
@@ -304,6 +304,10 @@ static int power7_generic_events[] = {
[PERF_COUNT_HW_CACHE_MISSES] = 0x400f0, /* LD_MISS_L1 */
[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = 0x10068, /* BRU_FIN */
[PERF_COUNT_HW_BRANCH_MISSES] = 0x400f6, /* BR_MPRED */
+ [PERF_COUNT_HW_STALLED_CYCLES_FIXED_POINT] = 0x20014,/* CMPLU_STALL_FXU */
+ [PERF_COUNT_HW_STALLED_CYCLES_LOAD_STORE] = 0x20012,/* CMPLU_STALL_LSU */
+ [PERF_COUNT_HW_STALLED_CYCLES_INSTRUCTION_FETCH] = 0x4004c,/* CMPLU_STALL_IFU */
+ [PERF_COUNT_HW_STALLED_CYCLES_BRANCH] = 0x4004e,/* CMPLU_STALL_BRU */
};
#define C(x) PERF_COUNT_HW_CACHE_##x
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index bdb4161..ff9f0a6 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -55,6 +55,10 @@ enum perf_hw_id {
PERF_COUNT_HW_STALLED_CYCLES_FRONTEND = 7,
PERF_COUNT_HW_STALLED_CYCLES_BACKEND = 8,
PERF_COUNT_HW_REF_CPU_CYCLES = 9,
+ PERF_COUNT_HW_STALLED_CYCLES_FIXED_POINT = 10,
+ PERF_COUNT_HW_STALLED_CYCLES_LOAD_STORE = 11,
+ PERF_COUNT_HW_STALLED_CYCLES_INSTRUCTION_FETCH = 12,
+ PERF_COUNT_HW_STALLED_CYCLES_BRANCH = 13,
PERF_COUNT_HW_MAX, /* non-ABI */
};
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 861f0ae..6275dbb 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -77,6 +77,10 @@ static struct perf_event_attr default_attrs[] = {
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_INSTRUCTIONS },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
{ .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_MISSES },
+ { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_FIXED_POINT },
+ { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_LOAD_STORE },
+ { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_INSTRUCTION_FETCH },
+ { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_BRANCH },
};
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 2eaae14..17e3190 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -77,6 +77,10 @@ static const char *perf_evsel__hw_names[PERF_COUNT_HW_MAX] = {
"stalled-cycles-frontend",
"stalled-cycles-backend",
"ref-cycles",
+ "stalled-cycles-fixed-point",
+ "stalled-cycles-load-store",
+ "stalled-cycles-instruction-fetch",
+ "stalled-cycles-branch",
};
static const char *__perf_evsel__hw_name(u64 config)
diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 384ca74..0c49c05 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -102,6 +102,10 @@ branch-instructions|branches { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_
branch-misses { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_COUNT_HW_BRANCH_MISSES); }
bus-cycles { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_COUNT_HW_BUS_CYCLES); }
ref-cycles { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_COUNT_HW_REF_CPU_CYCLES); }
+stalled-cycles-fixed-point { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_COUNT_HW_STALLED_CYCLES_FIXED_POINT); }
+stalled-cycles-load-store { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_COUNT_HW_STALLED_CYCLES_LOAD_STORE); }
+stalled-cycles-instruction-fetch { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_COUNT_HW_STALLED_CYCLES_INSTRUCTION_FETCH); }
+stalled-cycles-branch { return sym(yyscanner, PERF_TYPE_HARDWARE, PERF_COUNT_HW_STALLED_CYCLES_BRANCH); }
cpu-clock { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COUNT_SW_CPU_CLOCK); }
task-clock { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COUNT_SW_TASK_CLOCK); }
page-faults|faults { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COUNT_SW_PAGE_FAULTS); }
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 0688bfb..c563b30 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -952,6 +952,10 @@ static struct {
{ "COUNT_HW_STALLED_CYCLES_FRONTEND", PERF_COUNT_HW_STALLED_CYCLES_FRONTEND },
{ "COUNT_HW_STALLED_CYCLES_BACKEND", PERF_COUNT_HW_STALLED_CYCLES_BACKEND },
+ { "COUNT_HW_STALLED_CYCLES_FIXED_POINT", PERF_COUNT_HW_STALLED_CYCLES_FIXED_POINT },
+ { "COUNT_HW_STALLED_CYCLES_LOAD_STORE", PERF_COUNT_HW_STALLED_CYCLES_LOAD_STORE },
+ { "COUNT_HW_STALLED_CYCLES_INSTRUCTION_FETCH", PERF_COUNT_HW_STALLED_CYCLES_INSTRUCTION_FETCH },
+ { "COUNT_HW_STALLED_CYCLES_BRANCH", PERF_COUNT_HW_STALLED_CYCLES_BRANCH },
{ "COUNT_SW_CPU_CLOCK", PERF_COUNT_SW_CPU_CLOCK },
{ "COUNT_SW_TASK_CLOCK", PERF_COUNT_SW_TASK_CLOCK },
--
1.7.1
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