| Message ID | 20180327095535.17319-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Quoting Chris Wilson (2018-03-27 10:55:35) > Across suspend, we may see a very large drift in timestamps if the sched > clock is unstable, prompting the global trace's ringbuffer code to warn > and suggest switching to the global clock. Preempt this request by > detecting when the sched clock is unstable (determined during > late_initcall) and automatically switching the default clock over to > trace_global_clock. > > This should prevent requiring user interaction to resolve warnings such > as: > > Delta way too big! 18446743856563626466 ts=18446744054496180323 write stamp = 197932553857 > If you just came from a suspend/resume, > please switch to the trace global clock: > echo global > /sys/kernel/debug/tracing/trace_clock > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Any chance we can get this validated before poking Steven? -Chris > --- > kernel/trace/trace.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 13baf85b27d8..3e39aafb9bc1 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -41,6 +41,7 @@ > #include <linux/nmi.h> > #include <linux/fs.h> > #include <linux/trace.h> > +#include <linux/sched/clock.h> > #include <linux/sched/rt.h> > > #include "trace.h" > @@ -8484,6 +8485,13 @@ void __init trace_init(void) > trace_event_init(); > } > > +#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK > +static inline bool sched_clock_stable(void) > +{ > + return true; > +} > +#endif > + > __init static int clear_boot_tracer(void) > { > /* > @@ -8500,6 +8508,10 @@ __init static int clear_boot_tracer(void) > default_bootup_tracer); > default_bootup_tracer = NULL; > > + /* sched_clock_stable() is determined in late_initcall */ > + if (!trace_boot_clock && !sched_clock_stable()) > + tracing_set_clock(&global_trace, "global"); > + > return 0; > } > > -- > 2.16.3 >
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 13baf85b27d8..3e39aafb9bc1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -41,6 +41,7 @@ #include <linux/nmi.h> #include <linux/fs.h> #include <linux/trace.h> +#include <linux/sched/clock.h> #include <linux/sched/rt.h> #include "trace.h" @@ -8484,6 +8485,13 @@ void __init trace_init(void) trace_event_init(); } +#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK +static inline bool sched_clock_stable(void) +{ + return true; +} +#endif + __init static int clear_boot_tracer(void) { /* @@ -8500,6 +8508,10 @@ __init static int clear_boot_tracer(void) default_bootup_tracer); default_bootup_tracer = NULL; + /* sched_clock_stable() is determined in late_initcall */ + if (!trace_boot_clock && !sched_clock_stable()) + tracing_set_clock(&global_trace, "global"); + return 0; }
Across suspend, we may see a very large drift in timestamps if the sched clock is unstable, prompting the global trace's ringbuffer code to warn and suggest switching to the global clock. Preempt this request by detecting when the sched clock is unstable (determined during late_initcall) and automatically switching the default clock over to trace_global_clock. This should prevent requiring user interaction to resolve warnings such as: Delta way too big! 18446743856563626466 ts=18446744054496180323 write stamp = 197932553857 If you just came from a suspend/resume, please switch to the trace global clock: echo global > /sys/kernel/debug/tracing/trace_clock Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> --- kernel/trace/trace.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)