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Commit 8aacf017b065a805d27467843490c976835eb4a5

Authored by Steven Rostedt (Red Hat)
Committed by Steven Rostedt
1 parent 328df4759c
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

tracing: Add "uptime" trace clock that uses jiffies 

Add a simple trace clock called "uptime" for those that are
interested in the uptime of the trace. It uses jiffies as that's
the safest method, as other uptime clocks grab seq locks, which could
cause a deadlock if taken from an event or function tracer.

Requested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Showing 3 changed files with 12 additions and 0 deletions Side-by-side Diff

include/linux/trace_clock.h
Diff comments   View file @ 8aacf01
... ... @@ -16,6 +16,7 @@
16 16  
17 17 extern u64 notrace trace_clock_local(void);
18 18 extern u64 notrace trace_clock(void);
  19 +extern u64 notrace trace_clock_jiffies(void);
19 20 extern u64 notrace trace_clock_global(void);
20 21 extern u64 notrace trace_clock_counter(void);
21 22  
kernel/trace/trace.c
Diff comments   View file @ 8aacf01
... ... @@ -647,6 +647,7 @@
647 647 { trace_clock_local, "local", 1 },
648 648 { trace_clock_global, "global", 1 },
649 649 { trace_clock_counter, "counter", 0 },
  650 + { trace_clock_jiffies, "uptime", 1 },
650 651 ARCH_TRACE_CLOCKS
651 652 };
652 653  
kernel/trace/trace_clock.c
Diff comments   View file @ 8aacf01
... ... @@ -57,6 +57,16 @@
57 57 return local_clock();
58 58 }
59 59  
  60 +/*
  61 + * trace_jiffy_clock(): Simply use jiffies as a clock counter.
  62 + */
  63 +u64 notrace trace_clock_jiffies(void)
  64 +{
  65 + u64 jiffy = jiffies - INITIAL_JIFFIES;
  66 +
  67 + /* Return nsecs */
  68 + return (u64)jiffies_to_usecs(jiffy) * 1000ULL;
  69 +}
60 70  
61 71 /*
62 72 * trace_clock_global(): special globally coherent trace clock