Re: [PATCH v4 2/5] unpack-trees: add performance tracing

On 8/13/2018 6:41 PM, Junio C Hamano wrote:

Jeff King [off-list ref] writes:

quoted

I can buy the argument that it's nice to have some form of profiling
that works everywhere, even if it's lowest-common-denominator. I just
wonder if we could be investing effort into tooling around existing
solutions that will end up more powerful and flexible in the long run.

Another thing I noticed is that the codepaths we would find
interesting to annotate with trace_performance_* stuff often
overlaps with the "slog" thing.  If the latter aims to eventually
replace GIT_TRACE (and if not, I suspect there is not much point
adding it in the first place), perhaps we can extend it to also
cover the need of these trace_performance_* calls, so that we do not
have to carry three different tracing mechanisms.

I'm looking at adding code to my SLOG (better name suggestions welcome)
patch series to eventually replace the existing git_trace facility.
And I would like to have a set of nested messages like Duy has proposed
be a part of that.

In an independent effort I've found the nested messages being very
helpful in certain contexts.  They are not a replacement for the
various platform tools, like PerfView and friends as discussed earlier
on this thread, but then again I can ask a customer to turn a knob and
run it again and send me the output and hopefully get a rough idea of
the problem -- without having them install a bunch of perf tools.

Jeff