Horton

Re: WAL Insertion Lock Improvements

Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>

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From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Nathan Bossart <nathandbossart@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-05-09T04:04:56Z
Lists: pgsql-hackers 
On Tue, May 9, 2023 at 9:27 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Tue, May 09, 2023 at 09:24:14AM +0530, Bharath Rupireddy wrote:
> > I'll pick a test case that generates a reasonable amount of WAL 256
> > bytes. What do you think of the following?
> >
> > test-case 2: -T900, WAL ~256 bytes (for c in 1 2 4 8 16 32 64 128 256
> > 512 768 1024 2048 4096 - takes 3.5hrs)
> > test-case 2: -t1000000, WAL ~256 bytes
> >
> > If okay, I'll fire the tests.
>
> Sounds like a sensible duration, yes.  What's your setting for
> min/max_wal_size?  I assume that there are still 16GB throttled with
> target_completion at 0.9?

Below is the configuration I've been using. I have been keeping the
checkpoints away so far to get expected numbers. Probably, something
that I should modify for this long run? Change checkpoint_timeout to
15 min or so?

max_wal_size=64GB
checkpoint_timeout=1d
shared_buffers=8GB
max_connections=5000

-- 
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

Commits

  1. Optimize pg_atomic_exchange_u32 and pg_atomic_exchange_u64.

  2. Document more assumptions of LWLock variable changes with WAL inserts

  3. Optimize WAL insertion lock acquisition and release with some atomics

  4. Avoid the use of a separate spinlock to protect a LWLock's wait queue.