Re: [PATCH] trace-cmd: Make read nonblocking in find_time_stamp().

From: Steven Rostedt
Date: Mon Feb 09 2015 - 17:52:01 EST


On Mon, 4 Nov 2013 16:51:48 -0800
Aaron Fabbri <ajfabbri@xxxxxxxxx> wrote:

> This only affects the tsc -> time of day correlation when doing
> `trace-cmd record --date`.
>
> get_date_to_ts() writes a dummy event to trace_marker and then reads it back.
> Reading it back is done by looping over all per-cpu raw trace pipes and trying
> to read. This read should be non-blocking, because the dummy event can end up
> on any CPU.
>
> Signed-off-by: Aaron Fabbri <ajfabbri@xxxxxxxxx>

Hmm, I somehow missed this patch. I just applied (way late :-/), and
I'm placing it in the stable releases. I'm starting my testing now.

-- Steve

> ---
> trace-record.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/trace-record.c b/trace-record.c
> index 1b1d293..dca8a92 100644
> --- a/trace-record.c
> +++ b/trace-record.c
> @@ -2092,7 +2092,7 @@ static unsigned long long find_time_stamp(struct
> pevent *pevent)
> continue;
>
> sprintf(file, "%s/%s/trace_pipe_raw", path, name);
> - fd = open(file, O_RDONLY);
> + fd = open(file, O_RDONLY | O_NONBLOCK);
> if (fd < 0)
> continue;
> do {

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