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Re: PostgreSQL can't allocate shared memory [message #12055 is a reply to message #12032]

Mon, 16 April 2007 13:57

Gregor Mosheh
Messages: 62
Registered: April 2007

Member

>> And the HN's kernel.shmmax is set to 1 GB. (Is that relevant in a VE?)
> check the same in VE please.
> AFAICS, by default kernel sets:
> #define SHMMAX 0x2000000
> which is 32Mb.
> So you have to increase it in VE /etc/sysctl.conf file or in /proc.

Ahhh, very tricky -- in that it's exactly what one should expect! Thanks,
Kirill; I can't believe that this escaped me. I had thought that the VE
would have shmmax set by the UBC; evidently it's the case that each VE
gets their own set of sysctls for perfectly ordinary use.

So, let me summarize the shared memory situation for VEs:

* The HN's kernel.shmmax sets an absolute limit on shared memory,
for both the HN and any VEs.
* A VE's shmpages sets the limit on shared memory for that VE.
Therefore it must be <= kernel.shmmax
* Then the VE uses sysctl kernel.shmmax to set their allowable limit,
which of course must be <= the VE's shmpages.

Sound right?

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[Message index]

		PostgreSQL can't allocate shared memory By: Gregor Mosheh on Mon, 16 April 2007 05:42
		Re: PostgreSQL can't allocate shared memory By: dev on Mon, 16 April 2007 07:37
		Re: PostgreSQL can't allocate shared memory By: Gregor Mosheh on Mon, 16 April 2007 13:57
		Re: PostgreSQL can't allocate shared memory By: dev on Mon, 16 April 2007 17:32
		Re: PostgreSQL can't allocate shared memory By: Gregor Mosheh on Mon, 16 April 2007 17:40

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