Horton

Re: Atomics for heap_parallelscan_nextpage()

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Andres Freund <andres@anarazel.de>, David Rowley <david.rowley@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Amit Khandekar <amitdkhan.pg@gmail.com>, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>
Date: 2017-08-16T17:32:44Z
Lists: pgsql-hackers 
Heikki Linnakangas <hlinnaka@iki.fi> writes:
> On 08/16/2017 08:10 PM, Andres Freund wrote:
>> Seems like we'd just have to add alignment of the total size to
>> shm_toc_estimate()?

> Yeah, that's the gist of it.

I can confirm that on dromedary, that regression test case is attempting
to create a TOC with a not-well-aligned size: 93268 = 0x16c54 bytes.

			regards, tom lane

Commits

  1. Fix pg_atomic_u64 initialization.

  2. Fix shm_toc.c to always return buffer-aligned memory.

  3. Use atomic ops to hand out pages to scan in parallel scan.

  4. Improve 64bit atomics support.