Re: kern/51615: Userland processes not evenly distributed on all CPUs

[Hubert Feyrer <hubert%feyrer.de@localhost>]

The following reply was made to PR kern/51615; it has been noted by GNATS.

From: Hubert Feyrer <hubert%feyrer.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: Hubert Feyrer <hubert%feyrer.de@localhost>
Subject: Re: kern/51615: Userland processes not evenly distributed on all
 CPUs
Date: Wed, 9 Nov 2016 10:20:45 +0100 (CET)

 On Wed, 9 Nov 2016, Hubert Feyrer wrote:
 > Pondering on the "rounding error" mentioned by Michael, I've setup both VMs 
 > with 4 CPUs, and the behaviour shown there is that load is distributed to 
 > about 3 and a half CPU - three CPUs under full load, and one not reaching 
 > 100%. There's definitely something fishy in there.
 >
 > See screenshot:
 > http://www.feyrer.de/Misc/priv/bad-scheduling-7.0_STABLE+7.99.42-4CPUs.png
 
 Splitting up the four CPUs on different processor sets with one process 
 assigned to each set (using psrset(8)) leads to an even load distribution 
 here, too. This leads me to thinking that the NetBSD scheduling works well 
 between different processor sets, but is busted within one set.
 
 
   - Hubert