On Mon, Oct 14, 2019 at 1:25 PM dangal <danielito.gallo@xxxxxxxxx> wrote:
Do you think it should increase bgwriter_lru_maxpages due to the value of
maxwritten_clean?
I find the background writer to be pretty unimportant these days. If the kernel is freely accepting writes without blocking, the backends can probably write their own buffers without it being a meaningful bottleneck. On the other hand, if the kernel is constipated, no tweaking of the background writer parameters is going to insulate the backends from that fact. That said, I would increase bgwriter_lru_maxpages (or decrease
bgwriter_delay) anyway. It probably won't make much difference, but if it does it is more likely to help than to hurt.
Do you think it should increase bgwriter_lru_maxpages,
bgwriter_lru_multiplier, and decrease bgwriter_delay due to the value of
buffers_backend compared to buffers_alloc?
I don't think that that comparison is meaningful, so wouldn't make changes based on it.
Do you think a modification is necessary?
What values would you recommend?
thank you
If you are experiencing a problem, this is probably not the right way to investigate it. If a particular query is slow, try EXPLAIN (ANALYZE, BUFFERS). If lots of user-facing things are slow, try sampling "select wait_event, wait_event_type from pg_stat_activity where backend_type='client backend';"
