Re: [PATCH 05/16] tracing: show that buffer size is not expanded

KOSAKI Motohiro
2009-03-13T03:06:17Z

> From: Steven Rostedt <srostedt@redhat.com>
>
> Impact: do not confuse user on small trace buffer sizes
>
> When the system boots up, the trace buffer is small to conserve memory.
> It is only two pages per online CPU. When the tracer is used, it expands
> to the default value.
>
> This can confuse the user if they look at the buffer size and see only
> 7, but then later they see 1408.
>
> # cat /debug/tracing/buffer_size_kb
> 7
>
> # echo sched_switch > /debug/tracing/current_tracer
>
> # cat /debug/tracing/buffer_size_kb
> 1408
>
> This patch tries to help remove this confustion by showing that the
> buffer has not been expanded.
>
> # cat /debug/tracing/buffer_size_kb
> 7 (expanded: 1408)

Hi,

I have one question.
Why souldn't use following output?

sprintf(buf, "%lu\n", trace_buf_size >> 10);

My point is:
- pure number output can hadle easily.
- nobody need to know internal memory saving logic.