On 7/30/15 10:54 AM, Tom Lane wrote:
=?ISO-8859-15?Q?Jos=E9_Luis_Tall=F3n?= <jltal...@adv-solutions.net> writes:Since PostgreSQL lacks the resource management capabilities of the "Big Ones" ( Resource Groups - Red, WorkLoad Manager - Blue ) or the Resource Governor in MS SQL Server, we can try and approximate the requested behaviour by reducing the CPU priority ("nice") of the backend in question. Please note that we would be using scheduler priority to try and modulate I/O, though I'm aware of the limitations of this mechanism.This has been proposed before, and rejected before, and I'm not seeing anything particularly new here. Without a credible mechanism for throttling I/O, "nice" alone does not seem very promising.
Some OSes respect nice when it comes to IO scheduling, so it might still be useful. What I'm worried about is priority inversion[1].
What might be useful would be to add a set of GUCs similar to vacuum_cost_* that operated at the shared buffer level. Dunno where you'd put the sleep though (presumably all the functions where you'd put the accounting are too low-level to sleep in).
[1] https://en.wikipedia.org/wiki/Priority_inversion -- Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX Data in Trouble? Get it in Treble! http://BlueTreble.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
