perf tools: Add test for converting perf time to/from TSC

The test uses the newly added cap_usr_time_zero and time_zero of
perf_event_mmap_page.  TSC from rdtsc is compared with the time
from 2 perf events.  The test passes if the calculated times are
all in the correct order.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1372425741-1676-4-git-send-email-adrian.hunter@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 81 insertions, 0 deletions

diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile
index 815841c04eb2..8801fe02f206 100644
--- a/tools/perf/arch/x86/Makefile
+++ b/tools/perf/arch/x86/Makefile
@@ -6,3 +6,5 @@ ifndef NO_LIBUNWIND
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/unwind.o
 endif
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/header.o
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/tsc.o
+LIB_H += arch/$(ARCH)/util/tsc.h
diff --git a/tools/perf/arch/x86/util/tsc.c b/tools/perf/arch/x86/util/tsc.c
new file mode 100644
index 000000000000..f1117441cdcd
--- /dev/null
+++ b/tools/perf/arch/x86/util/tsc.c
@@ -0,0 +1,59 @@
+#include <stdbool.h>
+#include <errno.h>
+
+#include <linux/perf_event.h>
+
+#include "../../perf.h"
+#include "../../util/types.h"
+#include "../../util/debug.h"
+#include "tsc.h"
+
+u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
+{
+        u64 time, quot, rem;
+
+        time = ns - tc->time_zero;
+        quot = time / tc->time_mult;
+        rem  = time % tc->time_mult;
+        return (quot << tc->time_shift) +
+               (rem << tc->time_shift) / tc->time_mult;
+}
+
+u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
+{
+        u64 quot, rem;
+
+        quot = cyc >> tc->time_shift;
+        rem  = cyc & ((1 << tc->time_shift) - 1);
+        return tc->time_zero + quot * tc->time_mult +
+               ((rem * tc->time_mult) >> tc->time_shift);
+}
+
+int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
+                             struct perf_tsc_conversion *tc)
+{
+        bool cap_usr_time_zero;
+        u32 seq;
+        int i = 0;
+
+        while (1) {
+                seq = pc->lock;
+                rmb();
+                tc->time_mult = pc->time_mult;
+                tc->time_shift = pc->time_shift;
+                tc->time_zero = pc->time_zero;
+                cap_usr_time_zero = pc->cap_usr_time_zero;
+                rmb();
+                if (pc->lock == seq && !(seq & 1))
+                        break;
+                if (++i > 10000) {
+                        pr_debug("failed to get perf_event_mmap_page lock\n");
+                        return -EINVAL;
+                }
+        }
+
+        if (!cap_usr_time_zero)
+                return -EOPNOTSUPP;
+
+        return 0;
+}
diff --git a/tools/perf/arch/x86/util/tsc.h b/tools/perf/arch/x86/util/tsc.h
new file mode 100644
index 000000000000..a24dec81c795
--- /dev/null
+++ b/tools/perf/arch/x86/util/tsc.h
@@ -0,0 +1,20 @@
+#ifndef TOOLS_PERF_ARCH_X86_UTIL_TSC_H__
+#define TOOLS_PERF_ARCH_X86_UTIL_TSC_H__
+
+#include "../../util/types.h"
+
+struct perf_tsc_conversion {
+        u16 time_shift;
+        u32 time_mult;
+        u64 time_zero;
+};
+
+struct perf_event_mmap_page;
+
+int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
+                             struct perf_tsc_conversion *tc);
+
+u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc);
+u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc);
+
+#endif /* TOOLS_PERF_ARCH_X86_UTIL_TSC_H__ */