Re: postgresql latency & bgwriter not doing its job

On 2014-08-26 08:12:48 +0200, Fabien COELHO wrote:
> As for checkpoint spreading, raising checkpoint_completion_target to 0.9
> degrades the situation (20% of transactions are more than 200 ms late
> instead of 10%, bgwriter wrote less that 1 page per second, on on 500s run).
> So maybe there is a bug here somewhere.

What are the other settings here? checkpoint_segments,
checkpoint_timeout, wal_buffers?

Could you show the output of log_checkpoints during that run? Checkpoint
spreading only works halfway efficiently if all checkpoints are
triggered by "time" and not by "xlog".

Greetings,

Andres Freund

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