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

Hi Robert,

YES ! Reading this file, your suggestion should work ! Thx !

I've rebuilt and run the basic tests. We'll relaunch our tests asap.

Cordialement,

Tony Reix

tony(dot)reix(at)atos(dot)net

ATOS / Bull SAS
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IBM Coop Architect & Technical Leader
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________________________________
De : Robert Haas <robertmhaas(at)gmail(dot)com>
Envoyé : mardi 20 novembre 2018 15:53:11
À : REIX, Tony
Cc : pgsql-hackers(at)postgresql(dot)org; EMPEREUR-MOT, SYLVIE
Objet : Re: Shared Memory: How to use SYSV rather than MMAP ?

On Tue, Nov 20, 2018 at 8:36 AM REIX, Tony <tony(dot)reix(at)atos(dot)net> wrote:
> We are trying to understand why pgbench on AIX is slower compared to Linux/Power on the same HW/Disks.
>
> So, we have yet no idea about what may be the root cause and what should be changed.
>
> So, changing: dynamic_shared_memory_type = sysv seems to help.
>
> And maybe changing the main shared memory segment could also improve the performance. However, how one can change this?

There's no configuration setting for the main shared memory segment,
but removing #define USE_ANONYMOUS_SHMEM from sysv_shmem.c would
probably do the trick.

--
Robert Haas
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