Re: Noticed something odd with pgbench

On 16/11/12 19:35, Shaun Thomas wrote:
> Hey guys,
>
> So, we have a pretty beefy system that runs dual X5675's with 72GB of 
> RAM. After our recent upgrade to 9.1, things have been... odd. I 
> managed to track it down to one setting:
>
> shared_buffers = 8GB
>

> It does the same thing at 6GB. 4GB is safe for hours on end, but 6GB 
> and 8GB implode within in minutes. During this, kswapd goes crazy 
> paging out the cache, at the same time it's reading from disk to put 
> them back in. It's like I fed the kernel poison or something.
>
> Has anybody else noticed something like this? I got this behavior with 
> 9.1.6 on a 3.2 kernel. No amount of tweaks in /proc/sys/vm changed 
> anything either, so I'm not convinced it's a NUMA problem.
>
Does this match what you're seeing?

http://frosty-postgres.blogspot.co.uk/2012/08/postgresql-numa-and-zone-reclaim-mode.html