Re: [Qemu-devel] [PATCH for-2.10 0/2] trace: fix simpletrace.stp flight recorder mode

[Daniel P. Berrange]

On Mon, Aug 14, 2017 at 05:21:40PM +0100, Stefan Hajnoczi wrote:
> The SystemTap flight recorder mode no longer works with simpletrace.stp 
> because
> the event ID mapping records are emitted the first time an event fires.
> Chances are, the event ID mapping record will not be in ring buffer when the
> users wants to print the trace.
> 
> This series solves the issue by using the trace-events-all global event
> ordering for event IDs for simpletrace.stp.

I see the way you've written it means it'll still honour the event
id mappings in the header, if present, but I wonder what's the point
of keeping that anymore ? If we need to support this ring-buffer mode,
there's no way we can take advantage of having the ID mappings dynamically
defined - we must always guarantee a stable mapping.

IOW, should we just revert

  commit 7f1b588f20d027730676e627713ae3bbf6baab04
  Author: Daniel P. Berrange <address@hidden>
  Date:   Tue Oct 4 14:35:50 2016 +0100

    trace: emit name <-> ID mapping in simpletrace header
    
entirely ?


Regards,
Daniel
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