Re: Memory Allocation (8 GB shared buffer limit on Ubuntu Hardy) - Mailing list pgsql-performance

On Wed, Jan 7, 2009 at 3:23 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Frank Joerdens" <frank@joerdens.de> writes:
>> then I take the request size value from the error and do
>> echo 8810725376 > /proc/sys/kernel/shmmax
>> and get the same error again.
>
> What about shmall?

Yes that works, it was set to

root@db04:~# cat /proc/sys/kernel/shmall
2097152
root@db04:~# getconf PAGE_SIZE
4096

which is 2097152 * 4096 = 85899345920 (presumably a Ubuntu default),
i.e. slightly less than the required shmmax, which explains why 7 GB
works but 8 doesn't. 8810725376 / 4096 = 2151056 would appear to be
right, and indeed after doing

root@db04:~# echo 2151056 > /proc/sys/kernel/shmall

it works.

Thanks!

Frank