Re: Vacuuming the operating system documentation

On Sun, Jun 7, 2020 at 4:39 AM Magnus Hagander <magnus@hagander.net> wrote:>
> Oh they absolutely will. But most likely they will also use an older version of PostgreSQL because that's what their
enterpriseproduct supports. And we're not talking about removing the documentation from the old version (I'm
assuming).

Yeah, I wasn't planning on changing anything in backbranches.  It
sounds like we're OK with doing this for 13.  Here's a version with a
few more changes:

 * Drop mention of Linux oom_adj, per discussion.
 * Add paragraphs to each OS to point out what we actually expect you
to need to change (ie mostly nothing).
 * Drop mention of PG 9.2's requirements for more SysV shmem.  It made
sense to have that in there while versions with both behaviours were
still in circulation and you could have been looking at the wrong
version's manual, but that's stuff you can find in old release notes
if you're a historian.
 * Drop the paragraph that tells you what Linux's default SHMMAX is:
that has been wrong since 3.16.  The default is now sky high, a bit
under ULONG_MAX.
 * Drop the alternative way to set SHMMAX etc via /proc on Linux.
There's hardly any reason to do it at all, so describing two ways is
just wasting pixels.
 * Drop some more comments about ancient macOS.
 * Adjust the text that discusses adjusting shared_buffers if you
can't acquire enough SysV shmem, because that only makes sense if
shared_memory_type=sysv.
 * Point out that NetBSD's kern.ipc.shm_use_phys only applies to SysV
memory, as done for FreeBSD in the previous version.  I hadn't noticed
that NetBSD has that too, and I peeked at the source to check that
they only use that for SysV memory too.
 * Drop the text about recognising and reconfiguring kernels that were
built without SysV support; that's advice from another age.  Regular
users don't configure and build kernels, and those that do that don't
need these hints.  I am aware of one modern kernel that ships
pre-built without SysV IPC: Android, but apparently this stuff is also
missing from its libc so you won't get this far.