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authorAdrian Hunter <adrian.hunter@intel.com>2013-06-28 15:22:19 +0200
committerIngo Molnar <mingo@kernel.org>2013-07-23 12:17:59 +0200
commit3bd5a5fc8c6b9fe769777abf74b0ab5fbd7930b4 (patch)
treeac509b983fe147d6706449c3bc14031591807585 /tools/perf/arch
parentperf/x86: Add ability to calculate TSC from perf sample timestamps (diff)
downloadlinux-3bd5a5fc8c6b9fe769777abf74b0ab5fbd7930b4.tar.xz
linux-3bd5a5fc8c6b9fe769777abf74b0ab5fbd7930b4.zip
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>
Diffstat (limited to 'tools/perf/arch')
-rw-r--r--tools/perf/arch/x86/Makefile2
-rw-r--r--tools/perf/arch/x86/util/tsc.c59
-rw-r--r--tools/perf/arch/x86/util/tsc.h20
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__ */