| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Erik Rijkers <er(at)xs4all(dot)nl>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: testing HS/SR - 1 vs 2 performance |
| Date: | 2010-04-25 10:53:04 |
| Message-ID: | l2p603c8f071004250353o86f37300xadfa3331602549f8@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sat, Apr 24, 2010 at 5:17 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> Both Heikki and I objected to that patch.
>
> Please explain your objection, based upon the patch and my explanations.
Well, we objected to the locking. Having reread the patch a few times
though, I think I'm starting to wrap my head around it so, I don't
know, maybe it's OK. Have you tested grabbing the ProcArrayLock in
exclusive mode instead of having a separate spinlock, to see how that
performs?
>> And apparently it doesn't
>> fix the problem, either. So, -1 from me.
>
> There is an issue observed in Erik's later tests, but my interpretation
> of the results so far is that the sorted array patch successfully
> removes the initially reported loss of performance.
Is it possible the remaining spikes are due to fights over the spinlock?
...Robert
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