Re: [External Mail]Re: [RFC] tracing: aggregate ring-buffer usage statistics

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 12 Aug 2026 13:21:29 +0000
高翔 <gaoxiang17@xiaomi.com> wrote:

> Thanks, Steve.
> 
> For the initial implementation, I plan to add:
> 
>   /sys/kernel/tracing/trace_stats/total_memory_kb
> 
> The file would use an extensible key/value format. Initially it would
> report the ring-buffer data capacity:
> 
>   total:                   395664
>   ring_buffer:             395664
>   ring_buffer_live:        395544
>   ring_buffer_snapshot:       120

You can rename the above to:

   total:
   buffers_mem:
   snapshot_buffers_mem:

No need to use "ring" and it keeps consistent with "buffer_size_kb".

I added the "mem" part to distinguish the difference between these numbers
and the buffer_size_kb, as these numbers are about total memory whereas
the "buffer_size_kb" is about usable memory.

There's already a total for all memory listed. We don't need to have a
total for the "live" and "snapshot".

> 
> Here, ring_buffer is the sum of ring_buffer_live and
> ring_buffer_snapshot. The values cover the global trace array and all
> tracing instances across all tracing CPUs.
> 
> Additional accounted categories, such as event memory, could be appended
> later and included in total. Per-CPU statistics could be exposed
> separately under trace_stats/per_cpu/cpuN/ to avoid mixing aggregate and
> per-CPU values in one file.

Agreed, this file should exist in the cpuN/ directories and be only for
those instances.

> 
> Userspace would parse fields by name and ignore unknown fields, so new
> categories can be added without changing the existing format.

Right. I would expect additional items to be added here.

> 
> Does this initial format look reasonable?
> 

Yes, thanks for doing this.

-- Steve