Re: Performance TODO items - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Performance TODO items
Date
Msg-id 200107301715.f6UHFe310576@candle.pha.pa.us
Whole thread Raw
In response to Performance TODO items  (Bruce Momjian <pgman@candle.pha.pa.us>)
Responses Re: Performance TODO items  (Tom Lane <tgl@sss.pgh.pa.us>)
List 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)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026
 


pgsql-hackers by date:

Previous
From: Bruce Momjian
Date:
Subject: Performance TODO items
Next
From: "Mikheev, Vadim"
Date:
Subject: RE: Performance TODO items