Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?

Hi David,

Thanks for continuing to work on this patch, and my apologies for silence
on the patch.

Its been hard to make time, and especially so because I typically develop
on an ARM-based macOS system where I can't test this directly - hence my
tests with virtualized EC2 instances, where I ran into the timing oddities.

On Mon, Jan 2, 2023 at 5:28 AM David Geier <geidav(dot)pg(at)gmail(dot)com> wrote:

> The INSTR_TIME_GET_MICROSEC() returns a uint64 while the other variants
> return double. This seems error prone. What about renaming the function
> or also have the function return a double and cast where necessary at
> the call site?
>

Minor note, but in my understanding using a uint64 (where we can) is faster
for any simple arithmetic we do with the values.

> If no one objects I would also re-register this patch in the commit fest.
>

+1, and feel free to carry this patch forward - I'll try to make an effort
to review my earlier testing issues again, as well as your later
improvements to the patch.

Also, FYI, I just posted an alternate idea for speeding up EXPLAIN ANALYZE
with timing over in [0], using a sampling-based approach to reduce the
timing overhead.

[0]:
https://www.postgresql.org/message-id/CAP53PkxXMk0j-%2B0%3DYwRti2pFR5UB2Gu4v2Oyk8hhZS0DRART6g%40mail.gmail.com

Thanks,
Lukas

--
Lukas Fittl