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

Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> On 2018-Jul-19, Amit Kapila wrote:
>> It appears so.  I think we should do something about it as the
>> regression is quite noticeable.

It's not *that* noticeable, as I failed to demonstrate any performance
difference before committing the patch.  I think some more investigation
is warranted to find out why some other people are getting different
results.

> So the fix is just to revert the change for the linux makefile?  Sounds
> easy enough, code-wise.  Do we need more evidence that it's harmful?

Some fraction of 3d21f08bc would also need to be undone.  It's also worth
contemplating that we'd be re-introducing old problems with not-enough-
SysV-semaphores, so even if there is a performance benefit to be had,
it's very far from being free.

            regards, tom lane