Horton

Re: LogwrtResult contended spinlock

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, pgsql-hackers@lists.postgresql.org, Jaime Casanova <jcasanov@systemguards.com.ec>
Date: 2024-04-06T17:46:05Z
Lists: pgsql-hackers 
On Sat, 2024-04-06 at 18:13 +0200, Alvaro Herrera wrote:
> my understanding of pg_atomic_compare_exchange_u64 is that
> *expected is set to the value that's stored in *ptr prior to the
> exchange.

Sorry, my mistake. Your version looks good.

Regards,
	Jeff Davis

Commits

  1. Remove bogus assertion in pg_atomic_monotonic_advance_u64

  2. Add XLogCtl->logInsertResult

  3. Operate XLogCtl->log{Write,Flush}Result with atomics

  4. Split XLogCtl->LogwrtResult into separate struct members

  5. Introduce atomic read/write functions with full barrier semantics.

  6. Reduce the number of GetFlushRecPtr() calls done by walsenders.

  7. Remove most volatile qualifiers from xlog.c