Re: Performance TODO items

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От Bruce Momjian
Тема Re: Performance TODO items
Дата
Msg-id 200107301715.f6UHFe310576@candle.pha.pa.us
обсуждение исходный текст
Ответ на Performance TODO items  (Bruce Momjian <pgman@candle.pha.pa.us>)
Ответы Re: Performance TODO items  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
> > New TODO entries are:
> > 
> >     * Order duplicate index entries by tid
> 
> In other words - add tid to index key: very old idea.

I was thinking during index creation, it would be nice to order them by
tid, but not do lots of work to keep it that way.

> >     * Add queue of backends waiting for spinlock
> 
> We shouldn't mix two different approaches for different
> kinds of short-time internal locks - in one cases we need in
> light lmgr (when we're going to keep lock long enough, eg for IO)
> and in another cases we'd better to proceed with POSIX' mutex-es
> or semaphores instead of spinlocks. Queueing backends waiting
> for spinlock sounds like nonsense - how are you going to protect
> such queue? With spinlocks? -:)

Yes, I guess so but hopefully we can spin waiting for the queue lock
rather than sleep.  We could use POSIX spinlocks/semaphores now but we
don't because of performance, right?

Should we be spinning waiting for spinlock on multi-cpu machines?  Is
that the answer?

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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