Re: track_io_timing default setting

From: Stephen Frost <sfrost(at)snowman(dot)net>
To: Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: track_io_timing default setting
Date: 2021-12-22 19:16:16
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* Laurenz Albe (laurenz(dot)albe(at)cybertec(dot)at) wrote:
> On Fri, 2021-12-10 at 10:20 -0500, Tom Lane wrote:
> > Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> > > Can we change the default setting of track_io_timing to on?
> >
> > That adds a very significant amount of overhead on some platforms
> > (gettimeofday is not cheap if it requires a kernel call).  And I
> > doubt the claim that the average Postgres user needs this, and
> > doubt even more that they need it on all the time.
> > So I'm -1 on the idea.
> I set "track_io_timing" to "on" all the time, same as "log_lock_waits",
> so I'd want them both on by default.

Same. I'd also push back and ask what modern platforms still require a
kernel call for gettimeofday, and are we really doing ourselves a favor
by holding back on enabling this by default due to those? If it's such
an issue, could we figure out a way to have an 'auto' option where we
detect if the platform has such an issue and disable in that case, but
enable otherwise?



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