tracing: Unify the "boot" and "mono" tracing clocks
Unify the "boot" and "mono" tracing clocks and document the new behaviour. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kevin Easton <kevin@guarana.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Salyzyn <salyzyn@android.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20180301165150.489635255@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -449,17 +449,9 @@ of ftrace. Here is a list of some of the key files:
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which is montonic but is not subject to any rate adjustments
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and ticks at the same rate as the hardware clocksource.
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boot: This is the boot clock (CLOCK_BOOTTIME) and is based on the
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fast monotonic clock, but also accounts for time spent in
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suspend. Since the clock access is designed for use in
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tracing in the suspend path, some side effects are possible
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if clock is accessed after the suspend time is accounted before
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the fast mono clock is updated. In this case, the clock update
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appears to happen slightly sooner than it normally would have.
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Also on 32-bit systems, it's possible that the 64-bit boot offset
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sees a partial update. These effects are rare and post
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processing should be able to handle them. See comments in the
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ktime_get_boot_fast_ns() function for more information.
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boot: Same as mono. Used to be a separate clock which accounted
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for the time spent in suspend while CLOCK_MONOTONIC did
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not.
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To set a clock, simply echo the clock name into this file.
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@ -113,12 +113,6 @@ extern u64 ktime_get_mono_fast_ns(void);
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extern u64 ktime_get_raw_fast_ns(void);
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extern u64 ktime_get_real_fast_ns(void);
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/* Clock BOOTTIME compatibility wrappers */
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static inline u64 ktime_get_boot_fast_ns(void)
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{
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return ktime_get_mono_fast_ns();
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}
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/*
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* timespec64 interfaces utilizing the ktime based ones
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*/
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@ -1164,7 +1164,7 @@ static struct {
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{ trace_clock, "perf", 1 },
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{ ktime_get_mono_fast_ns, "mono", 1 },
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{ ktime_get_raw_fast_ns, "mono_raw", 1 },
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{ ktime_get_boot_fast_ns, "boot", 1 },
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{ ktime_get_mono_fast_ns, "boot", 1 },
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ARCH_TRACE_CLOCKS
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};
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