On Thu, 12 Sep 2013 23:04:01 +0800
Wang YanQing <[email protected]> wrote:
>
> Cat snapshot give me:
> " tracer: nop
>
> * Snapshot is freed *
>
> Snapshot commands:
> echo 0 > snapshot : Clears and frees snapshot buffer
> echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.
> Takes a snapshot of the main buffer.
> echo 2 > snapshot : Clears snapshot buffer (but does not allocate)
> (Doesn't have to be '2' works with any number that
> is not a '0' or '1')"
>
> But after read the code, I found the right information about "echo 2 >
> snapshot"
> should looks like below:
>
> " echo 2 > snapshot : Clears snapshot buffer (but does not free)
> (Doesn't have to be '2' works with any number that
> is not a '0' or '1')"
Actually, they both are correct:
default:
if (tr->allocated_snapshot) {
if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
tracing_reset_online_cpus(&tr->max_buffer);
else
tracing_reset(&tr->max_buffer, iter->cpu_file);
}
break;
}
It does nothing if it isn't allocated.
Perhaps we need it to say "(but does not allocate or free)"
-- Steve
>
> Signed-off-by: Wang YanQing <[email protected]>
> ---
> kernel/trace/trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 7974ba2..d0da660 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -2760,7 +2760,7 @@ static void show_snapshot_main_help(struct seq_file *m)
> seq_printf(m, "# echo 0 > snapshot : Clears and frees snapshot
> buffer\n");
> seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not
> already allocated.\n");
> seq_printf(m, "# Takes a snapshot of the main
> buffer.\n");
> - seq_printf(m, "# echo 2 > snapshot : Clears snapshot buffer (but does
> not allocate)\n");
> + seq_printf(m, "# echo 2 > snapshot : Clears snapshot buffer (but does
> not free)\n");
> seq_printf(m, "# (Doesn't have to be '2' works
> with any number that\n");
> seq_printf(m, "# is not a '0' or '1')\n");
> }
--
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