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

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

[Aaron Fabbri]

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@gmail.com>
---
 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 {
-- 
1.8.1.2

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

[Steven Rostedt]

On Mon, 4 Nov 2013 16:51:48 -0800
Aaron Fabbri <ajfabbri@gmail.com> 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@gmail.com>

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 {