Re: checkpointer continuous flushing
От | Fabien COELHO |
---|---|
Тема | Re: checkpointer continuous flushing |
Дата | |
Msg-id | alpine.DEB.2.10.1506230700260.31285@sto обсуждение исходный текст |
Ответ на | Re: checkpointer continuous flushing (Andres Freund <andres@anarazel.de>) |
Список | pgsql-hackers |
> I'd also like to see concurrent workloads with synchronous_commit=off - > I've seen absolutely horrible latency behaviour for that, and I'm hoping > this will help. It's also a good way to simulate faster hardware than > you have. It helps. I've done a few runs, where the very-very-bad situation is improved to... I would say very-bad: medium3: scale=200 shared_buffers=4GB checkpoint_timeout=15min max_wal_size=4GB warmup=1200 time=6000 clients=4 synchronous_commit=off flush sort | tps | percent of seconds offline off off | 296 | 83% offline off on | 1496 | 33% offline off on | 1641 | 59% offline on on | 1515 | 31% offline The offline figure is the percentage of seconds in the 6000 seconds run where 0.0 tps are reported, or where nothing is reported because pgbench is stuck. It is somehow better... on an abysmal scale: sorting and flushing reduced the offline time by a factor of 2.6. Too bad it is so high to begin with. The tps is improved by a factor of 5 with either options. -- Fabien.
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