Re: Possible performance regression in version 10.1 with pgbench read-write tests.

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>
To: Mithun Cy <mithun.cy@enterprisedb.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2018-02-22T14:25:28Z
Lists: pgsql-hackers
On Wed, Feb 21, 2018 at 10:03 PM, Mithun Cy <mithun.cy@enterprisedb.com> wrote:
> seeing futex in the call stack andres suggested that following commit could
> be the reason for regression
>
> commit ecb0d20a9d2e09b7112d3b192047f711f9ff7e59
> Author: Tom Lane <tgl@sss.pgh.pa.us>
> Date:   2016-10-09 18:03:45 -0400
>
>     Use unnamed POSIX semaphores, if available, on Linux and FreeBSD.
>
> Commenting out same in src/template/linux I did run the benchmark tests
> again
> performance improved from 26871.567326 to 34286.620251 (both median of 3
> TPS).

Hmm.  So that commit might not have been the greatest idea.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


Commits

  1. Pad semaphores to avoid false sharing.