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

Hi Robert,


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?


Cordialement,

Tony Reix

tony.reix@atos.net

ATOS / Bull SAS
ATOS Expert
IBM Coop Architect & Technical Leader
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________________________________
De : Robert Haas <robertmhaas@gmail.com>
Envoyé : mardi 20 novembre 2018 13:53:53
À : REIX, Tony
Cc : pgsql-hackers@postgresql.org; EMPEREUR-MOT, SYLVIE
Objet : Re: Shared Memory: How to use SYSV rather than MMAP ?

On Tue, Nov 20, 2018 at 5:11 AM REIX, Tony <tony.reix@atos.net> wrote:
> On AIX, since with MMAP we have only 4K pages though we can have 64K pages with SYSV, we'd like to experiment with SYSV rather than MMAP and measure the impact to the performance.

Are you trying to move the main shared memory segment or the dynamic
shared memory segments?

--
Robert Haas
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