Re: Adjustment of spinlock sleep delays

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Rod Taylor <rbt(at)rbt(dot)ca>
Cc: PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Adjustment of spinlock sleep delays
Date: 2003-08-05 22:19:24
Message-ID: 13525.1060121964@sss.pgh.pa.us
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Rod Taylor <rbt(at)rbt(dot)ca> writes:
> After the first few sleeps should it add a random() element to the delay
> time?

Hmm, that's a thought --- but how big a random element?

Fooling with the original idea, I'm having trouble with getting both
plausible backoff and a reasonable number of attempts before failing.
I tried the sequence

10 msec, 20 msec, 40, 80, ..., 1280 (1.28 sec), repeat

but this only gives a couple of hundred tries before one minute has
elapsed, which seems uncomfortably low. Maybe there's no alternative,
though, if we want any good-sized delays in there.

regards, tom lane

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