Re: LogwrtResult contended spinlock

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Alexander Lakhin <exclusion@gmail.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Andres Freund <andres@anarazel.de>, Jeff Davis <pgsql@j-davis.com>, pgsql-hackers@lists.postgresql.org, Jaime Casanova <jcasanov@systemguards.com.ec>
Date: 2024-07-01T14:08:23Z
Lists: pgsql-hackers
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
>> because the failed assertion is:
>> #ifndef PG_HAVE_ATOMIC_U64_SIMULATION
>>     AssertPointerAlignment(&currval, 8);
>> #endif

Perhaps this assertion is what is wrong?  If the platform has no
native 8-byte alignment requirement, why do we think that atomics
need it?

			regards, tom lane



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