Commit-ID: 2924ecd441f3c12da59b297daade265f49d0831b Gitweb: http://git.kernel.org/tip/2924ecd441f3c12da59b297daade265f49d0831b Author: Joel Fernandes <joelaf@xxxxxxxxxx> AuthorDate: Mon, 28 Nov 2016 14:35:24 -0800 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Tue, 29 Nov 2016 18:03:00 +0100 trace: Update documentation for mono, mono_raw and boot clock Documentation was missing for mono and mono_raw, add them and also for the boot clock introduced in this series. Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Prarit Bhargava <prarit@xxxxxxxxxx> Cc: Richard Cochran <richardcochran@xxxxxxxxx> Link: http://lkml.kernel.org/r/1480372524-15181-8-git-send-email-john.stultz@xxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- Documentation/trace/ftrace.txt | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 185c39f..5596e2d 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -362,6 +362,26 @@ of ftrace. Here is a list of some of the key files: to correlate events across hypervisor/guest if tb_offset is known. + mono: This uses the fast monotonic clock (CLOCK_MONOTONIC) + which is monotonic and is subject to NTP rate adjustments. + + mono_raw: + This is the raw monotonic clock (CLOCK_MONOTONIC_RAW) + which is montonic but is not subject to any rate adjustments + and ticks at the same rate as the hardware clocksource. + + boot: This is the boot clock (CLOCK_BOOTTIME) and is based on the + fast monotonic clock, but also accounts for time spent in + suspend. Since the clock access is designed for use in + tracing in the suspend path, some side effects are possible + if clock is accessed after the suspend time is accounted before + the fast mono clock is updated. In this case, the clock update + appears to happen slightly sooner than it normally would have. + Also on 32-bit systems, it's possible that the 64-bit boot offset + sees a partial update. These effects are rare and post + processing should be able to handle them. See comments in the + ktime_get_boot_fast_ns() function for more information. + To set a clock, simply echo the clock name into this file. echo global > trace_clock -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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