[PATCH v3 3/3] selftests: Add test of PMU instruction counting on powerpc
Michael Ellerman
michael at ellerman.id.au
Tue Aug 6 17:42:37 EST 2013
This commit adds a test of instruction counting using the PMU on powerpc.
Although the bulk of the code is architecture agnostic, the code needs to
run a precisely sized loop which is implemented in assembler.
Signed-off-by: Michael Ellerman <michael at ellerman.id.au>
---
v2,3: No change
tools/testing/selftests/powerpc/Makefile | 2 +-
tools/testing/selftests/powerpc/pmu/Makefile | 23 ++++
.../selftests/powerpc/pmu/count_instructions.c | 135 +++++++++++++++++++++
tools/testing/selftests/powerpc/pmu/event.c | 105 ++++++++++++++++
tools/testing/selftests/powerpc/pmu/event.h | 39 ++++++
tools/testing/selftests/powerpc/pmu/loop.S | 46 +++++++
6 files changed, 349 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/powerpc/pmu/Makefile
create mode 100644 tools/testing/selftests/powerpc/pmu/count_instructions.c
create mode 100644 tools/testing/selftests/powerpc/pmu/event.c
create mode 100644 tools/testing/selftests/powerpc/pmu/event.h
create mode 100644 tools/testing/selftests/powerpc/pmu/loop.S
diff --git a/tools/testing/selftests/powerpc/Makefile b/tools/testing/selftests/powerpc/Makefile
index b315740..bd24ae5 100644
--- a/tools/testing/selftests/powerpc/Makefile
+++ b/tools/testing/selftests/powerpc/Makefile
@@ -13,7 +13,7 @@ CFLAGS := -Wall -O2 -flto -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(CUR
export CC CFLAGS
-TARGETS =
+TARGETS = pmu
endif
diff --git a/tools/testing/selftests/powerpc/pmu/Makefile b/tools/testing/selftests/powerpc/pmu/Makefile
new file mode 100644
index 0000000..7216f00
--- /dev/null
+++ b/tools/testing/selftests/powerpc/pmu/Makefile
@@ -0,0 +1,23 @@
+noarg:
+ $(MAKE) -C ../
+
+PROGS := count_instructions
+EXTRA_SOURCES := ../harness.c event.c
+
+all: $(PROGS)
+
+$(PROGS): $(EXTRA_SOURCES)
+
+# loop.S can only be built 64-bit
+count_instructions: loop.S count_instructions.c $(EXTRA_SOURCES)
+ $(CC) $(CFLAGS) -m64 -o $@ $^
+
+run_tests: all
+ @-for PROG in $(PROGS); do \
+ ./$$PROG; \
+ done;
+
+clean:
+ rm -f $(PROGS) loop.o
+
+.PHONY: all run_tests clean
diff --git a/tools/testing/selftests/powerpc/pmu/count_instructions.c b/tools/testing/selftests/powerpc/pmu/count_instructions.c
new file mode 100644
index 0000000..312b4f0
--- /dev/null
+++ b/tools/testing/selftests/powerpc/pmu/count_instructions.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright 2013, Michael Ellerman, IBM Corp.
+ * Licensed under GPLv2.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/prctl.h>
+
+#include "event.h"
+#include "utils.h"
+
+extern void thirty_two_instruction_loop(u64 loops);
+
+static void setup_event(struct event *e, u64 config, char *name)
+{
+ event_init_opts(e, config, PERF_TYPE_HARDWARE, name);
+
+ e->attr.disabled = 1;
+ e->attr.exclude_kernel = 1;
+ e->attr.exclude_hv = 1;
+ e->attr.exclude_idle = 1;
+}
+
+static int do_count_loop(struct event *events, u64 instructions,
+ u64 overhead, bool report)
+{
+ s64 difference, expected;
+ double percentage;
+
+ prctl(PR_TASK_PERF_EVENTS_ENABLE);
+
+ /* Run for 1M instructions */
+ thirty_two_instruction_loop(instructions >> 5);
+
+ prctl(PR_TASK_PERF_EVENTS_DISABLE);
+
+ event_read(&events[0]);
+ event_read(&events[1]);
+
+ expected = instructions + overhead;
+ difference = events[0].result.value - expected;
+ percentage = (double)difference / events[0].result.value * 100;
+
+ if (report) {
+ event_report(&events[0]);
+ event_report(&events[1]);
+
+ printf("Looped for %llu instructions, overhead %llu\n", instructions, overhead);
+ printf("Expected %llu\n", expected);
+ printf("Actual %llu\n", events[0].result.value);
+ printf("Delta %lld, %f%%\n", difference, percentage);
+ }
+
+ event_reset(&events[0]);
+ event_reset(&events[1]);
+
+ if (difference < 0)
+ difference = -difference;
+
+ /* Tolerate a difference below 0.0001 % */
+ difference *= 10000 * 100;
+ if (difference / events[0].result.value)
+ return -1;
+
+ return 0;
+}
+
+/* Count how many instructions it takes to do a null loop */
+static u64 determine_overhead(struct event *events)
+{
+ u64 current, overhead;
+ int i;
+
+ do_count_loop(events, 0, 0, false);
+ overhead = events[0].result.value;
+
+ for (i = 0; i < 100; i++) {
+ do_count_loop(events, 0, 0, false);
+ current = events[0].result.value;
+ if (current < overhead) {
+ printf("Replacing overhead %llu with %llu\n", overhead, current);
+ overhead = current;
+ }
+ }
+
+ return overhead;
+}
+
+static int count_instructions(void)
+{
+ struct event events[2];
+ u64 overhead;
+
+ setup_event(&events[0], PERF_COUNT_HW_INSTRUCTIONS, "instructions");
+ setup_event(&events[1], PERF_COUNT_HW_CPU_CYCLES, "cycles");
+
+ if (event_open(&events[0])) {
+ perror("perf_event_open");
+ return -1;
+ }
+
+ if (event_open_with_group(&events[1], events[0].fd)) {
+ perror("perf_event_open");
+ return -1;
+ }
+
+ overhead = determine_overhead(events);
+ printf("Overhead of null loop: %llu instructions\n", overhead);
+
+ /* Run for 1M instructions */
+ FAIL_IF(do_count_loop(events, 0x100000, overhead, true));
+
+ /* Run for 10M instructions */
+ FAIL_IF(do_count_loop(events, 0xa00000, overhead, true));
+
+ /* Run for 100M instructions */
+ FAIL_IF(do_count_loop(events, 0x6400000, overhead, true));
+
+ /* Run for 1G instructions */
+ FAIL_IF(do_count_loop(events, 0x40000000, overhead, true));
+
+ event_close(&events[0]);
+ event_close(&events[1]);
+
+ return 0;
+}
+
+int main(void)
+{
+ return test_harness(count_instructions, "count_instructions");
+}
diff --git a/tools/testing/selftests/powerpc/pmu/event.c b/tools/testing/selftests/powerpc/pmu/event.c
new file mode 100644
index 0000000..2b2d11d
--- /dev/null
+++ b/tools/testing/selftests/powerpc/pmu/event.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2013, Michael Ellerman, IBM Corp.
+ * Licensed under GPLv2.
+ */
+
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <string.h>
+#include <stdio.h>
+#include <sys/ioctl.h>
+
+#include "event.h"
+
+
+int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu,
+ int group_fd, unsigned long flags)
+{
+ return syscall(__NR_perf_event_open, attr, pid, cpu,
+ group_fd, flags);
+}
+
+void event_init_opts(struct event *e, u64 config, int type, char *name)
+{
+ memset(e, 0, sizeof(*e));
+
+ e->name = name;
+
+ e->attr.type = type;
+ e->attr.config = config;
+ e->attr.size = sizeof(e->attr);
+ /* This has to match the structure layout in the header */
+ e->attr.read_format = PERF_FORMAT_TOTAL_TIME_ENABLED | \
+ PERF_FORMAT_TOTAL_TIME_RUNNING;
+}
+
+void event_init_named(struct event *e, u64 config, char *name)
+{
+ event_init_opts(e, config, PERF_TYPE_RAW, name);
+}
+
+#define PERF_CURRENT_PID 0
+#define PERF_NO_CPU -1
+#define PERF_NO_GROUP -1
+
+int event_open_with_options(struct event *e, pid_t pid, int cpu, int group_fd)
+{
+ e->fd = perf_event_open(&e->attr, pid, cpu, group_fd, 0);
+ if (e->fd == -1) {
+ perror("perf_event_open");
+ return -1;
+ }
+
+ return 0;
+}
+
+int event_open_with_group(struct event *e, int group_fd)
+{
+ return event_open_with_options(e, PERF_CURRENT_PID, PERF_NO_CPU, group_fd);
+}
+
+int event_open(struct event *e)
+{
+ return event_open_with_options(e, PERF_CURRENT_PID, PERF_NO_CPU, PERF_NO_GROUP);
+}
+
+void event_close(struct event *e)
+{
+ close(e->fd);
+}
+
+int event_reset(struct event *e)
+{
+ return ioctl(e->fd, PERF_EVENT_IOC_RESET);
+}
+
+int event_read(struct event *e)
+{
+ int rc;
+
+ rc = read(e->fd, &e->result, sizeof(e->result));
+ if (rc != sizeof(e->result)) {
+ fprintf(stderr, "read error on event %p!\n", e);
+ return -1;
+ }
+
+ return 0;
+}
+
+void event_report_justified(struct event *e, int name_width, int result_width)
+{
+ printf("%*s: result %*llu ", name_width, e->name, result_width,
+ e->result.value);
+
+ if (e->result.running == e->result.enabled)
+ printf("running/enabled %llu\n", e->result.running);
+ else
+ printf("running %llu enabled %llu\n", e->result.running,
+ e->result.enabled);
+}
+
+void event_report(struct event *e)
+{
+ event_report_justified(e, 0, 0);
+}
diff --git a/tools/testing/selftests/powerpc/pmu/event.h b/tools/testing/selftests/powerpc/pmu/event.h
new file mode 100644
index 0000000..e699319
--- /dev/null
+++ b/tools/testing/selftests/powerpc/pmu/event.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2013, Michael Ellerman, IBM Corp.
+ * Licensed under GPLv2.
+ */
+
+#ifndef _SELFTESTS_POWERPC_PMU_EVENT_H
+#define _SELFTESTS_POWERPC_PMU_EVENT_H
+
+#include <unistd.h>
+#include <linux/perf_event.h>
+
+#include "utils.h"
+
+
+struct event {
+ struct perf_event_attr attr;
+ char *name;
+ int fd;
+ /* This must match the read_format we use */
+ struct {
+ u64 value;
+ u64 running;
+ u64 enabled;
+ } result;
+};
+
+void event_init(struct event *e, u64 config);
+void event_init_named(struct event *e, u64 config, char *name);
+void event_init_opts(struct event *e, u64 config, int type, char *name);
+int event_open_with_options(struct event *e, pid_t pid, int cpu, int group_fd);
+int event_open_with_group(struct event *e, int group_fd);
+int event_open(struct event *e);
+void event_close(struct event *e);
+int event_reset(struct event *e);
+int event_read(struct event *e);
+void event_report_justified(struct event *e, int name_width, int result_width);
+void event_report(struct event *e);
+
+#endif /* _SELFTESTS_POWERPC_PMU_EVENT_H */
diff --git a/tools/testing/selftests/powerpc/pmu/loop.S b/tools/testing/selftests/powerpc/pmu/loop.S
new file mode 100644
index 0000000..8820e3d
--- /dev/null
+++ b/tools/testing/selftests/powerpc/pmu/loop.S
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2013, Michael Ellerman, IBM Corp.
+ * Licensed under GPLv2.
+ */
+
+ .text
+
+ .global thirty_two_instruction_loop
+ .type .thirty_two_instruction_loop, at function
+ .section ".opd","aw", at progbits
+thirty_two_instruction_loop:
+ .quad .thirty_two_instruction_loop, .TOC. at tocbase, 0
+ .previous
+.thirty_two_instruction_loop:
+ cmpwi %r3,0
+ beqlr
+ addi %r4,%r3,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1
+ addi %r4,%r4,1 # 28 addi's
+ subi %r3,%r3,1
+ b .thirty_two_instruction_loop
--
1.8.1.2
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