From: Balkrishna Sharma <b_ki@hotmail.com>
To: pgsql-admin@postgresql.org
Subject: Relation between RAM / shmmax / shmall / shared_buffers
Date: Tue, 25 May 2010 14:05:11 -0400
Message-ID: <BAY149-w5102A9288345674F2C689AF0E80@phx.gbl> (raw)
Hi,
I am having a transactional database heavy on parallel reads and updates. Apart from hardware optimization, I want to ensure that my system parameters are optimized as well. Following is what I am doing on my test system having 4GB RAM. Please let me know if the logic sounds ok (at least at high-level) and if there are other related parameters I should tweak as well:
RAM = 4GB1. Keeping the kernel parameter kernel.shmmax at 75% of RAM (i.e. at 3GB )kernel.shmmax = 32212254722. Keeping the kernel parameter shmall at the same value. Because shmall is measured in number of pages and each page on my linux is 4096 bytes, having kernel.shmall = 786432 (786432 * 4096 = 3221225472, same as shmmax)3. Keeping the shared_buffer parameter in the postgresql.conf file to be 25% of the kernel.shmmax. i.e. shared_buffers = 768MB (25% of 3072 MB)
Thanks,-Bala
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To: pgsql-admin@postgresql.org
Cc: b_ki@hotmail.com
Subject: Re: Relation between RAM / shmmax / shmall / shared_buffers
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