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help / color / mirror / Atom feedFrom: bricklen <[email protected]>
To: Charles Nadeau <[email protected]>
Cc: postgres performance list <[email protected]>
Subject: Re: Very poor read performance, query independent
Date: Wed, 12 Jul 2017 07:11:54 -0700
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On Wed, Jul 12, 2017 at 12:30 AM, Charles Nadeau <[email protected]>
wrote:
>
> I use noop as the scheduler because it is better to let the RAID
> controller re-arrange the IO operation before they reach the disk. Read
> ahead is set to 128:
>
> charles@hpdl380g6:~$ cat /sys/block/sdc/queue/read_ahead_kb
> 128
> charles@hpdl380g6:~$ cat /sys/block/sdc/queue/scheduler
> [noop] deadline cfq
>
>
>
Perhaps pg_test_fsync (
https://www.postgresql.org/docs/9.6/static/pgtestfsync.html) and
pg_test_timing will help shed some light here, or at the very least give
some numbers to compare against.
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