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    Subject[PATCH 06/10] tracing: Add unstable sched clock note to the warning
    From: Jiri Olsa <jolsa@redhat.com>

    The warning "Delta way too big" warning might appear on a system with
    unstable shed clock right after the system is resumed and tracing
    was enabled during the suspend.

    Since it's not realy bug, and the unstable sched clock is working
    fast and reliable otherwise, Steven suggested to keep using the
    sched clock in any case and just to make note in the warning itself.

    Signed-off-by: Jiri Olsa <jolsa@redhat.com>
    LKML-Reference: <1296649698-6003-1-git-send-email-jolsa@redhat.com>
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
    ---
    kernel/trace/ring_buffer.c | 8 ++++++--
    1 files changed, 6 insertions(+), 2 deletions(-)

    diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
    index bd1c35a..7739893 100644
    --- a/kernel/trace/ring_buffer.c
    +++ b/kernel/trace/ring_buffer.c
    @@ -2163,10 +2163,14 @@ rb_reserve_next_event(struct ring_buffer *buffer,
    delta = diff;
    if (unlikely(test_time_stamp(delta))) {
    WARN_ONCE(delta > (1ULL << 59),
    - KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n",
    + KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
    (unsigned long long)delta,
    (unsigned long long)ts,
    - (unsigned long long)cpu_buffer->write_stamp);
    + (unsigned long long)cpu_buffer->write_stamp,
    + sched_clock_stable ? "" :
    + "If you just came from a suspend/resume,\n"
    + "please switch to the trace global clock:\n"
    + " echo global > /sys/kernel/debug/tracing/trace_clock\n");
    add_timestamp = 1;
    }
    }
    --
    1.7.2.3



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