Re: Estimating HugePages Requirements? - Mailing list pgsql-hackers

From Bossart, Nathan
Subject Re: Estimating HugePages Requirements?
Date
Msg-id 0545F7B3-70C0-4DE8-8C85-EAFE6113B7EE@amazon.com
Whole thread Raw
In response to Re: Estimating HugePages Requirements?  (Andres Freund <andres@anarazel.de>)
Responses Re: Estimating HugePages Requirements?  (Michael Paquier <michael@paquier.xyz>)
List pgsql-hackers
On 8/9/21, 8:43 PM, "Andres Freund" <andres@anarazel.de> wrote:
> I don't like putting this into PostmasterMain(). Either BootstrapMain()
> (specifically checker mode) or GucInfoMain() seem like better places.

I think BootstrapModeMain() makes the most sense.  It fits in nicely
with the --check logic that's already there.  With v3, the following
command can be used to retrieve the amount of shared memory required.

        postgres --output-shmem -D dir

While testing this new option, I noticed that you can achieve similar
results today with the following command, although this one will
actually try to create the shared memory, too.

        postgres --check -D dir -c log_min_messages=debug3 2> >(grep IpcMemoryCreate)

IMO the new option is still handy, but I can see the argument that it
might not be necessary.

> That seems like an ugly API to me. Why don't we split the size
> determination and shmem creation functions into two?

I did it this way in v3.

Nathan


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