Em Thu, May 27, 2010 at 01:54:46PM -0700, Arun Sharma escreveu:
Excellent point, but as time goes on we may end up selecting all the
optionally selectable fields, so perhaps we should tell that to record
and then check at report time if it is present?
For instance, PERF_SAMPLE_TIME would be interesting too to check if
there is no reordering of events, etc, but should we have it always
enabled?
If we used something like:
perf record --sort cpu,comm ...
We would be able for instance, to avoid having MMAP events that wouldn't
be used at all, reducing PERF_SAMPLE_TID too, I guess, and then the per
event cost would be reduced, on the other hand, if we want to have
maximum flexibility at 'report' time, we could use:
perf record --sort all
With the default remaining the one we have.
perf record --sort +cpu
could be used to add one field to the set of fields in place, whatever
we get the default to be at any point in time.
perf record could as well, if no --sort is presented, infer a reasonable
one from the set of fields present in sample_type, etc.
Of course the feature implemented as-is by your patch is useful and we
need to support it, it can even be like you posted, but I wanted to
express this feeling about per event cost.
Will try to get it done now and will send for review.
- Arnaldo
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