Re: Postgresql on an AMD64 machine - Mailing list pgsql-performance

According to my research, you only need a 64 bit image if you are going
to be doing intensive floating point operations (which most db servers
don't do).  Some benchmarking results I've found on the internet
indicate that 64 bit executables can be slower than 32 bit versions.
I've been running 32 bit compiles on solaris for several years.

How much memory do you have on that sparc box?  Allocating more than
about 7-12% to shared buffers has proven counter productive for us (it
slows down).

Kernel buffers are another animal. :)

Donald Courtney wrote:
> Get FATAL when starting up (64 bit) with large shared_buffers setting
>
> I built a 64 bit for Sparc/Solaris easily but I found  that the
> startup of postmaster generates a FATAL diagnostic due to going
> over the 2GB limit (3.7 GB).
>
> When building for 64 bit is there some other
> things that must change in order to size UP the shared_buffers?
>
> Thanks.
>
> Don C.
>
> P.S.  A severe checkpoint problem I was having was fixed with
> "checkpoint_segments=200".
>
>
> Message:
>
> FATAL:  460000 is outside the valid range for parameter "shared_buffers"
> (16 .. 262143)
> LOG:  database system was shut down at 2005-06-07 15:20:28 EDT
>
> Mike Rylander wrote:
>
>> On 06 Jun 2005 12:53:40 -0500, Mark Rinaudo <mark@bowmansystems.com>
>> wrote:
>>
>>
>>> I'm not sure if this is the appropriate list to post this question to
>>> but i'm starting with this one because it is related to the performance
>>> of Postgresql server.  I have a Penguin Computing dual AMD 64 bit
>>> opteron machine with 8 Gigs of memory.  In my attempt to increase the
>>> number of shared_buffers from the default to 65000 i was running into a
>>> semget error when trying to start Postgresql. After reading the
>>> documentation I adjusted the semaphore settings in the kernel to allow
>>> Postgresql to start successfully.  With this configuration running if I
>>> do a ipcs -u i get the following.
>>>
>>
>>
>>
>> On my HP-585, 4xOpteron, 16G RAM, Gentoo Linux (2.6.9):
>>
>> $ ipcs -u i
>>
>> ------ Shared Memory Status --------
>> segments allocated 1
>> pages allocated 34866
>> pages resident  31642
>> pages swapped   128
>> Swap performance: 0 attempts     0 successes
>>
>> ------ Semaphore Status --------
>> used arrays = 7
>> allocated semaphores = 119
>>
>> ------ Messages: Status --------
>> allocated queues = 0
>> used headers = 0
>> used space = 0 bytes
>>
>>
>> Did you perhaps disable spinlocks when compiling PG?
>>
>>
>>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: Have you checked our extensive FAQ?
>
>               http://www.postgresql.org/docs/faq
>
>
>