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    Subject[tip:perf/core] tracing: Add unstable sched clock note to the warning
    Commit-ID:  5e38ca8f3ea423442eaafe1b7e206084aa38120a
    Gitweb: http://git.kernel.org/tip/5e38ca8f3ea423442eaafe1b7e206084aa38120a
    Author: Jiri Olsa <jolsa@redhat.com>
    AuthorDate: Wed, 2 Feb 2011 13:28:18 +0100
    Committer: Steven Rostedt <rostedt@goodmis.org>
    CommitDate: Tue, 8 Feb 2011 11:57:22 -0500

    tracing: Add unstable sched clock note to the warning

    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;
    }
    }

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