From: Chris Wilson <chris@chris-wilson.co.uk> To: linux-kernel@vger.kernel.org Cc: intel-gfx@lists.freedesktop.org, Chris Wilson <chris@chris-wilson.co.uk>, Steven Rostedt <rostedt@goodmis.org> Subject: [PATCH] trace: Default to using trace_global_clock if sched_clock is unstable Date: Thu, 29 Mar 2018 23:25:57 +0100 [thread overview] Message-ID: <20180329222557.6274-1-chris@chris-wilson.co.uk> (raw) 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> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> --- kernel/trace/trace.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 13baf85b27d8..c5462513db90 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" @@ -8505,3 +8506,15 @@ __init static int clear_boot_tracer(void) fs_initcall(tracer_init_tracefs); late_initcall_sync(clear_boot_tracer); + +#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK +__init static int tracing_set_default_clock(void) +{ + /* sched_clock_stable() is determined in late_initcall */ + if (!trace_boot_clock && !sched_clock_stable()) + tracing_set_clock(&global_trace, "global"); + + return 0; +} +late_initcall_sync(tracing_set_default_clock); +#endif -- 2.16.3
WARNING: multiple messages have this Message-ID (diff)
From: Chris Wilson <chris@chris-wilson.co.uk> To: linux-kernel@vger.kernel.org Cc: intel-gfx@lists.freedesktop.org, Steven Rostedt <rostedt@goodmis.org> Subject: [PATCH] trace: Default to using trace_global_clock if sched_clock is unstable Date: Thu, 29 Mar 2018 23:25:57 +0100 [thread overview] Message-ID: <20180329222557.6274-1-chris@chris-wilson.co.uk> (raw) 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> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> --- kernel/trace/trace.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 13baf85b27d8..c5462513db90 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" @@ -8505,3 +8506,15 @@ __init static int clear_boot_tracer(void) fs_initcall(tracer_init_tracefs); late_initcall_sync(clear_boot_tracer); + +#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK +__init static int tracing_set_default_clock(void) +{ + /* sched_clock_stable() is determined in late_initcall */ + if (!trace_boot_clock && !sched_clock_stable()) + tracing_set_clock(&global_trace, "global"); + + return 0; +} +late_initcall_sync(tracing_set_default_clock); +#endif -- 2.16.3 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next reply other threads:[~2018-03-29 22:26 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-29 22:25 Chris Wilson [this message] 2018-03-29 22:25 ` [PATCH] trace: Default to using trace_global_clock if sched_clock is unstable Chris Wilson 2018-03-29 22:36 ` ✗ Fi.CI.CHECKPATCH: warning for trace: Default to using trace_global_clock if sched_clock is unstable (rev2) Patchwork 2018-03-29 22:51 ` ✓ Fi.CI.BAT: success " Patchwork 2018-03-30 3:10 ` ✗ Fi.CI.IGT: failure " Patchwork 2018-03-30 13:48 ` [PATCH] trace: Default to using trace_global_clock if sched_clock is unstable Steven Rostedt 2018-03-30 13:48 ` Steven Rostedt 2018-03-30 14:07 ` Chris Wilson 2018-03-30 14:37 ` Steven Rostedt 2018-03-30 14:37 ` Steven Rostedt
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