Re: Adjustment of spinlock sleep delays
От | Rod Taylor |
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Тема | Re: Adjustment of spinlock sleep delays |
Дата | |
Msg-id | 1060123675.19206.12.camel@jester обсуждение исходный текст |
Ответ на | Re: Adjustment of spinlock sleep delays (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: Adjustment of spinlock sleep delays
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Список | pgsql-hackers |
On Tue, 2003-08-05 at 18:19, Tom Lane wrote: > Rod Taylor <rbt@rbt.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. How about (round to nearest 10msec): time = oldtime + oldtime / 2 + oldtime * rand() while (time > 1 second)time = time - 0.80sec This would stagger the wakeup times, and ensure a larger number of retries -- but the times should be large enough after the first few tries (larger than 200msec) that further backoff won't be required.
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