From: David Sharp <dhsharp@google.com>
To: linux-kernel@vger.kernel.org
Cc: David Sharp <dhsharp@google.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Subject: [PATCH 1/3] tracing,x86: add a TSC trace_clock; reset buffer on clock change
Date: Wed, 12 Sep 2012 16:31:57 -0700 [thread overview]
Message-ID: <1347492720-26078-2-git-send-email-dhsharp@google.com> (raw)
In-Reply-To: <1347492720-26078-1-git-send-email-dhsharp@google.com>
In order to promote interoperability between userspace tracers and ftrace,
add a trace_clock that reports raw TSC values which will then be recorded
in the ring buffer. Userspace tracers that also record TSCs are then on
exactly the same time base as the kernel and events can be unambiguously
interlaced.
Tested: Enabled a tracepoint and the "tsc" trace_clock and saw very large
timestamp values.
Google-Bug-Id: 6980623
Signed-off-by: David Sharp <dhsharp@google.com>
---
include/linux/trace_clock.h | 3 +++
kernel/trace/trace.c | 3 +++
kernel/trace/trace_clock.c | 16 ++++++++++++++++
3 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/include/linux/trace_clock.h b/include/linux/trace_clock.h
index 4eb4902..b86c7363 100644
--- a/include/linux/trace_clock.h
+++ b/include/linux/trace_clock.h
@@ -16,5 +16,8 @@ extern u64 notrace trace_clock_local(void);
extern u64 notrace trace_clock(void);
extern u64 notrace trace_clock_global(void);
extern u64 notrace trace_clock_counter(void);
+#ifdef CONFIG_X86_TSC
+extern u64 notrace trace_clock_tsc(void);
+#endif
#endif /* _LINUX_TRACE_CLOCK_H */
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5c38c81..dc1f1fa 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -480,6 +480,9 @@ static struct {
{ trace_clock_local, "local" },
{ trace_clock_global, "global" },
{ trace_clock_counter, "counter" },
+#ifdef CONFIG_X86_TSC
+ { trace_clock_tsc, "tsc" },
+#endif
};
int trace_clock_id;
diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c
index 3947835..1770737 100644
--- a/kernel/trace/trace_clock.c
+++ b/kernel/trace/trace_clock.c
@@ -125,3 +125,19 @@ u64 notrace trace_clock_counter(void)
{
return atomic64_add_return(1, &trace_counter);
}
+
+#ifdef CONFIG_X86_TSC
+/*
+ * trace_clock_tsc(): A clock that is just the cycle counter.
+ *
+ * Unlike the other clocks, this is not in nanoseconds.
+ */
+u64 notrace trace_clock_tsc(void)
+{
+ u64 ret;
+ rdtsc_barrier();
+ rdtscll(ret);
+
+ return ret;
+}
+#endif
--
1.7.7.3
next prev parent reply other threads:[~2012-09-13 0:37 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-12 2:41 [PATCH 0/3] TSC trace_clock David Sharp
2012-09-12 2:41 ` [PATCH 1/3] tracing,x86: add a TSC trace_clock; reset buffer on clock change David Sharp
2012-09-12 3:48 ` Steven Rostedt
2012-09-12 18:48 ` David Sharp
2012-09-12 2:41 ` [PATCH 2/3] tracing: reset ring buffer when changing trace_clocks David Sharp
2012-09-12 2:41 ` [PATCH 3/3] tracing: format non-nanosec times from tsc clock without a decimal point David Sharp
2012-09-12 23:31 ` [PATCH v2 0/3] TSC trace_clock David Sharp
2012-09-12 23:31 ` David Sharp [this message]
2012-09-12 23:31 ` [PATCH v2 1/3] tracing,x86: add a " David Sharp
2012-09-13 1:15 ` Masami Hiramatsu
2012-09-13 1:23 ` Steven Rostedt
2012-09-18 21:37 ` David Sharp
2012-09-18 21:37 ` [PATCH v2 2/3] tracing: reset ring buffer when changing trace_clocks David Sharp
2012-09-18 21:37 ` [PATCH v2 3/3] tracing: format non-nanosec times from tsc clock without a decimal point David Sharp
2012-09-19 2:10 ` [PATCH v2 1/3] tracing,x86: add a TSC trace_clock Steven Rostedt
2012-09-20 8:55 ` Ingo Molnar
2012-09-20 13:34 ` Steven Rostedt
2012-09-20 22:52 ` [PATCH v3 " David Sharp
2012-09-20 22:52 ` [PATCH v3 2/3] tracing: reset ring buffer when changing trace_clocks David Sharp
2012-09-20 22:52 ` [PATCH v3 3/3] tracing: format non-nanosec times from tsc clock without a decimal point David Sharp
2012-09-25 3:27 ` Steven Rostedt
2012-09-25 20:48 ` David Sharp
2012-09-25 20:49 ` [PATCH v4 " David Sharp
2012-09-25 21:42 ` Steven Rostedt
2012-09-25 22:29 ` David Sharp
2012-09-25 22:29 ` David Sharp
2012-09-26 18:30 ` Steven Rostedt
2012-09-26 21:03 ` David Sharp
2012-09-25 23:36 ` Steven Rostedt
2012-09-26 0:32 ` David Sharp
2012-09-29 3:15 ` [PATCH v3 1/3] tracing,x86: add a TSC trace_clock Steven Rostedt
2012-10-02 0:33 ` David Sharp
2012-10-02 0:43 ` Steven Rostedt
2012-09-20 22:53 ` [PATCH v2 " David Sharp
2012-09-18 21:46 ` David Sharp
2012-09-12 23:31 ` [PATCH v2 2/3] tracing: reset ring buffer when changing trace_clocks David Sharp
2012-09-12 23:32 ` [PATCH v2 3/3] tracing: format non-nanosec times from tsc clock without a decimal point David Sharp
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