Re: SLRU optimization - configurable buffer pool and partitioning the SLRU lock

On Tue, Feb 6, 2024 at 8:55 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>
> Here's the rest of it rebased on top of current master. I think it
> makes sense to have this as one individual commit.
>
> I made CLOGShmemBuffers, CommitTsShmemBuffers and SUBTRANSShmemBuffers
> compute a number that's multiple of SLRU_BANK_SIZE. But it's a crock,
> because we don't have that macro at that point, so I just used constant
> 16. Obviously need a better solution for this.

If we define SLRU_BANK_SIZE in slur.h then we can use it here right,
because these files are anyway include slur.h so.

>
> I also changed the location of bank_mask in SlruCtlData for better
> packing, as advised by pahole; and renamed SLRU_SLOTNO_GET_BANKLOCKNO()
> to SlotGetBankNumber().

Okay.

> Some very critical comments still need to be updated to the new design,
> particularly anything that mentions "control lock"; but also the overall
> model needs to be explained in some central location, rather than
> incongruently some pieces here and other pieces there. I'll see about
> this later. But at least this is code you should be able to play with.

Okay, I will review and test this

> I've been wondering whether we should add a "slru" to the name of the
> GUCs:
>
> commit_timestamp_slru_buffers
> transaction_slru_buffers
> etc

I am not sure we are exposing anything related to SLRU to the user, I
mean transaction_buffers should make sense for the user that it stores
transaction-related data in some buffers pool but whether that buffer
pool is called SLRU or not doesn't matter much to the user IMHO.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com