[RFC][PATCH 6/6] perf, tools: X86 RDPMC, RDTSC test

[Peter Zijlstra]

Implement a simple test for the self-monitoring data from the
mmap-control page.

 6: x86 rdpmc test: Ok
0: 6042 2481
1: 60042 23669
2: 605410 245588
3: 6060818 2396231

XXX: come up with logic to automagically turn these numbers into OK/FAIL.

Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Arun Sharma <asharma@xxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
 tools/perf/builtin-test.c |  129 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
Index: linux-2.6/tools/perf/builtin-test.c
===================================================================
--- linux-2.6.orig/tools/perf/builtin-test.c
+++ linux-2.6/tools/perf/builtin-test.c
@@ -14,6 +14,8 @@
 #include "util/thread_map.h"
 #include "../../include/linux/hw_breakpoint.h"
 
+#include <sys/mman.h>
+
 static long page_size;
 
 static int vmlinux_matches_kallsyms_filter(struct map *map __used, struct symbol *sym)
@@ -841,6 +843,127 @@ static int test__parse_events(void)
 
 	return ret;
 }
+
+#if defined(__x86_64__) || defined(__i386__)
+
+#define barrier() asm volatile("" ::: "memory")
+
+static u64 rdpmc(unsigned int counter)
+{
+	unsigned int low, high;
+
+	asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));
+
+	return low | ((u64)high) << 32;
+}
+
+static u64 rdtsc(void)
+{
+	unsigned int low, high;
+
+	asm volatile("rdtsc" : "=a" (low), "=d" (high));
+
+	return low | ((u64)high) << 32;
+}
+
+static u64 mmap_read_self(void *addr, u64 *enabled, u64 *running)
+{
+	struct perf_event_mmap_page *pc = addr;
+	u32 seq;
+	u64 count, delta;
+
+	do {
+again:
+		seq = pc->lock;
+		barrier();
+		if (seq & 1)
+			goto again;
+
+		if ((enabled || running) && pc->time_mult) {
+			u64 cyc = rdtsc();
+			u64 rem, quot;
+
+			quot = (cyc >> pc->time_shift);
+			rem = cyc & ((1 << pc->time_shift) - 1);
+			delta = pc->time_offset +
+				quot * pc->time_mult +
+				((rem * pc->time_mult) >> pc->time_shift);
+		}
+
+		if (enabled)
+			*enabled = pc->time_enabled + delta;
+
+		if (running)
+			*running = pc->time_running + delta;
+
+		if (pc->index) {
+			count = rdpmc(pc->index - 1);
+			count += pc->offset;
+		} else
+			goto fail;
+
+		barrier();
+	} while (pc->lock != seq);
+
+	return count;
+
+fail:
+	/*
+	 * XXX do read() here
+	 */
+	printf("FAIL FAIL FAIL\n");
+	return 0;
+}
+
+static int test__rdpmc(void)
+{
+	volatile int tmp = 0;
+	int loops = 1000;
+	int n, i;
+	int fd;
+	void *addr;
+	struct perf_event_attr attr = {
+		.type = PERF_TYPE_HARDWARE,
+		.config = PERF_COUNT_HW_INSTRUCTIONS,
+	};
+
+
+	fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
+	if (fd < 0) {
+		die("Error: sys_perf_event_open() syscall returned "
+		    "with %d (%s)\n", fd, strerror(errno));
+	}
+
+	addr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
+	if (addr == (void *)(-1)) {
+		die("Error: mmap() syscall returned "
+		    "with (%s)\n", strerror(errno));
+	}
+
+	for (n = 0; n < 4; n++) {
+
+		u64 stamp, now;
+		u64 stamp2, now2;
+
+		stamp = mmap_read_self(addr, NULL, &stamp2);
+
+		for (i = 0; i < loops; i++)
+			tmp++;
+
+		now = mmap_read_self(addr, NULL, &now2);
+		loops *= 10;
+
+		printf("%d: %Lu %Lu\n", n, (unsigned long long)(now - stamp),
+					   (unsigned long long)(now2 - stamp2));
+	}
+
+	munmap(addr, page_size);
+	close(fd);
+
+	return 0;
+}
+#endif
+
 static struct test {
 	const char *desc;
 	int (*func)(void);
@@ -865,6 +988,12 @@ static struct test {
 		.desc = "parse events tests",
 		.func = test__parse_events,
 	},
+#if defined(__x86_64__) || defined(__i386__)
+	{
+		.desc = "x86 rdpmc test",
+		.func = test__rdpmc,
+	},
+#endif
 	{
 		.func = NULL,
 	},


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