Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation)

On Tue, Feb 6, 2018 at 1:04 PM, Tomas Vondra
<tomas.vondra@2ndquadrant.com> wrote:
> Did you do a test with "-O0"? In my experience that makes valgrind tests
> much more reliable and repeatable. Some time ago we've seen cases that
> were failing for me but not for others, and I suspect it was due to me
> using "-O0".

FWIW, I use -O1 when configure is run for Valgrind. I also turn off
assertions (this is all scripted). According to the Valgrind manual:

"With -O1 line numbers in error messages can be inaccurate, although
generally speaking running Memcheck on code compiled at -O1 works
fairly well, and the speed improvement compared to running -O0 is
quite significant. Use of -O2 and above is not recommended as Memcheck
occasionally reports uninitialised-value errors which don’t really
exist."

The manual does also say that there might even be some problems with
-O1 at a later point, but it sounds like it's probably worth it to me.
Skink uses -Og, FWIW.

--
Peter Geoghegan