| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> |
| Cc: | Ants Aasma <ants(at)cybertec(dot)at>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, "Tharakan, Robins" <tharar(at)amazon(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: track_planning causing performance regression |
| Date: | 2020-07-01 16:54:25 |
| Message-ID: | 20200701165425.urkb2dtckms5bena@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
Hi,
On 2020-07-01 22:20:50 +0900, Fujii Masao wrote:
> On 2020/07/01 4:03, Andres Freund wrote:
> > Why did you add the hashing here? It seems a lot better to just add an
> > lwlock in-place instead of the spinlock? The added size is neglegible
> > compared to the size of pgssEntry.
>
> Because pgssEntry is not array entry but hashtable entry. First I was
> thinking to assign per-process lwlock to each entry in the array at the
> startup. But each entry is created every time new entry is required.
> So lwlock needs to be assigned to each entry at that creation time.
> We cannnot easily assign lwlock to all the entries at the startup.
But why not just do it exactly at the place the SpinLockInit() is done
currently?
Greetings,
Andres Freund
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