| From: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Julien Cigar <jcigar(at)ulb(dot)ac(dot)be>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: shared_buffers/effective_cache_size on 96GB server |
| Date: | 2012-10-10 17:05:20 |
| Message-ID: | CAGTBQpZ0E2xyAeNZy6a4uyhzyfhSNMv3TRDeLWdeT16RYYMPOg@mail.gmail.com |
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| Lists: | pgsql-performance |
On Wed, Oct 10, 2012 at 1:10 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>> >shared_buffers = 10GB
>>
>> Generally going over 4GB for shared_buffers doesn't help.. some of
>> the overhead of bgwriter and checkpoints is more or less linear in
>> the size of shared_buffers ..
>>
>> >effective_cache_size = 90GB
>>
>> effective_cache_size should be ~75% of the RAM (if it's a dedicated server)
>
> Why guess? Use 'free' to tell you the kernel cache size:
>
> http://momjian.us/main/blogs/pgblog/2012.html#May_4_2012
Why does nobody every mention that concurrent access has to be taken
into account?
Ie: if I expect concurrent access to 10 really big indices, I'll set
effective_cache_size = free ram / 10
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