Re: Disabling bgwriter on my notebook

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Jan Wieck <JanWieck(at)Yahoo(dot)com>, Michael Paesold <mpaesold(at)gmx(dot)at>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Disabling bgwriter on my notebook
Date: 2004-09-20 22:28:12
Message-ID: 200409202228.i8KMSCb01223@candle.pha.pa.us
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What about the original request to turn off the bgwriter? Would setting
the delay to a very high value do that?

---------------------------------------------------------------------------

Tom Lane wrote:
> Jan Wieck <JanWieck(at)Yahoo(dot)com> writes:
> >>> bgwriter_delay = 50 (now default 200)
> >>> bgwriter_percent = 2 (now default 1)
> >>> bgwriter_maxpages = 200 (now default 100)
>
> > Just what I was having the best TPC-C results with.
>
> I'm a bit hesitant to reduce the default bgwriter_delay, since AFAICS
> that will result in a direct increase in the CPU overhead incurred.
> (It'd be nice if the bgwriter didn't have to scan through *all* the
> buffers on every cycle ...)
>
> If we keep the delay at 200 then the 50/2 numbers would be roughly
> equivalent to 200/8, that is flush 8% every 200ms. I'm inclined to
> propose 5% as the default bgwriter_percent --- what do you think?
>
> We need not change the maxpages default since it wouldn't matter until
> you had upwards of 2000 dirty buffers, which to me would indicate that
> you had better be raising the other parameters anyway (and you could
> never get there at all with the default shared_buffers setting).
>
> regards, tom lane
>
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