Re: Shared Memory: How to use SYSV rather than MMAP ?

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, "REIX, Tony" <tony.reix@atos.net>, Andres Freund <andres@anarazel.de>, Pg Hackers <pgsql-hackers@postgresql.org>, "EMPEREUR-MOT, SYLVIE" <sylvie.empereur-mot@atos.net>
Date: 2018-12-26T18:57:49Z
Lists: pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> On Wed, Dec 26, 2018 at 11:43 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'm -1 on making this user configurable via a GUC; that adds documentation
>> and compatibility burdens that we don't need, for something of no value
>> to 99.99% of users.
> ...
> You may be right that this is of no value to a high percentage our
> users, but I think that's only because a high percentage of our users
> run Linux or Windows, which happen not to be affected. I'm rather
> proud, though, of PostgreSQL's long history of trying to be
> cross-platform. Even if operating systems like AIX or BSD are a small
> percentage of the overall user base, I think it's totally fair to add
> a GUC which likely be helpful to a large percentage of those people,
> and I think the GUC proposed here likely falls into that category.

You misread what I said.  I don't say that we shouldn't fix this;
what I'm saying is we should not do so via a user-configurable knob.
We should be able to auto-configure this and just handle it internally.
I have zero faith in the idea that users would set the knob correctly.

			regards, tom lane


Commits

  1. Add shared_memory_type GUC.

  2. Dramatically reduce System V shared memory consumption.