Re: WAL Insertion Lock Improvements

On Wed, May 10, 2023 at 10:40:20PM +0530, Bharath Rupireddy wrote:
> test-case 2: -T900, WAL ~256 bytes - ran for about 3.5 hours and the
> more than 3X improvement in TPS is seen - 3.11X @ 512 3.79 @ 768, 3.47
> @ 1024, 2.27 @ 2048, 2.77 @ 4096
>
> [...]
>
> test-case 2: -t1000000, WAL ~256 bytes - ran for more than 12 hours
> and the maximum improvement is 1.84X @ 1024 client.

Thanks. So that's pretty close to what I was seeing when it comes to
this message size where you see much more effects under a number of
clients of at least 512~. Any of these tests have been using fsync =
on, I assume. I think that disabling fsync or just mounting pg_wal to
a tmpfs should show the same pattern for larger record sizes (after 1k
of message size the curve begins to go down with 512~ clients).
--
Michael