Skip site navigation (1) Skip section navigation (2)

Re: Vacuum rate limit in KBps

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Greg Smith <greg(at)2ndquadrant(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Vacuum rate limit in KBps
Date: 2012-01-29 23:29:42
Message-ID: CAMkU=1yM2WxUx8TZe=2ZG-wfFwMHCh-OmeV3ZQOEBuymH4i06Q@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Sun, Jan 15, 2012 at 12:24 AM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:

> If you then turn that equation around, making the maximum write rate the
> input, for any given cost delay and dirty page cost you can solve for the
> cost limit--the parameter in fictitious units everyone hates.  It works like
> this, with the computation internals logged every time they run for now:
>
> #vacuum_cost_rate_limit = 4000      # maximum write rate in kilobytes/second
> LOG:  cost limit=200 based on rate limit=4000 KB/s delay=20 dirty cost=20

The computation seems to be suffering from some kind of overflow:

cost limit=50 based on rate limit=1000 KB/s delay=20 dirty cost=20
cost limit=100 based on rate limit=2000 KB/s delay=20 dirty cost=20
cost limit=150 based on rate limit=3000 KB/s delay=20 dirty cost=20
cost limit=200 based on rate limit=4000 KB/s delay=20 dirty cost=20
cost limit=250 based on rate limit=5000 KB/s delay=20 dirty cost=20
cost limit=1 based on rate limit=6000 KB/s delay=20 dirty cost=20
cost limit=1 based on rate limit=7000 KB/s delay=20 dirty cost=20
cost limit=1 based on rate limit=8000 KB/s delay=20 dirty cost=20

Cheers,

Jeff

In response to

pgsql-hackers by date

Next:From: Alvaro HerreraDate: 2012-01-30 01:07:06
Subject: Re: cursors FOR UPDATE don't return most recent row
Previous:From: Simon RiggsDate: 2012-01-29 23:04:47
Subject: Re: CLOG contention, part 2

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group