Date: Fri, 2 Dec 2022 16:31:58 -0800
From: Nathan Bossart <nathandbossart@gmail.com>
To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Cc: Andres Freund <andres@anarazel.de>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: WAL Insertion Lock Improvements (was: Re: Avoid
 LWLockWaitForVar() for currently held WAL insertion lock in
 WaitXLogInsertionsToFinish())
Message-ID: <20221203003158.GA2518778@nathanxps13>
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On Fri, Dec 02, 2022 at 04:32:38PM +0530, Bharath Rupireddy wrote:
> On Fri, Dec 2, 2022 at 6:10 AM Andres Freund <andres@anarazel.de> wrote:
>> I'm not sure this is quite right - don't we need a memory barrier. But I don't
>> see a reason to not just leave this code as-is. I think this should be
>> optimized entirely in lwlock.c
> 
> Actually, we don't need that at all as LWLockWaitForVar() will return
> immediately if the lock is free. So, I removed it.

I briefly looked at the latest patch set, and I'm curious how this change
avoids introducing memory ordering bugs.  Perhaps I am missing something
obvious.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com