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From: Ron Johnson <[email protected]>
To: pgsql-general <[email protected]>
Subject: Re: Posgresql 14 and CarbonBlack on RHEL8?
Date: Wed, 1 May 2024 04:44:16 -0400
Message-ID: <CANzqJaBUzsKzGhGyhUNk1kXNqixOOL9RoKi3G323aVacFu0WpA@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CANzqJaBybDrzRfjseKPS+3EhBFrLuU_kfSFME_2+VSoR-DLOdw@mail.gmail.com>
	<[email protected]>

On Tue, Apr 30, 2024 at 10:07 PM Tom Lane <[email protected]> wrote:

> Ron Johnson <[email protected]> writes:
> > When running stress tests on the systems (in prod, during the maintenance
> > window), 171K events/second are generated on the RHEL8 servers, and CB
> > needs (according to top(1)) 325% of CPU to handle that, and still
> dropping
> > 92% of them.
> > The RHEL6 system doesn't bat an eye at running the exact same test (36
> cron
> > jobs running psql executing SELECT statements).
>
> Is JIT enabled on the newer system?  If so try turning it off, or else
> raise the associated cost settings.  We've seen lots of reports of
> workloads where, by default, the planner is too aggressive about
> applying JIT.
>

A puzzling suggestion.  Why should it impact AV software?

At one point, I disabled JIT to test its impact on PG, performance was a
bit of a wash (some queries were a bit faster, some were a bit slower), but
I didn't monitor CB.

Just now, I did ALTER SYSTEM SET jit='off'; and re-ran the stress test.  No
impact to CarbonBlack.

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