[Mauiusers] fairshare - a better way to calculate percentages?

Åke Sandgren ake.sandgren at hpc2n.umu.se
Wed Jun 17 22:02:05 MDT 2009


On Wed, 2009-06-17 at 14:07 -0400, Michael Barnes wrote:
> On Tue, Jun 16, 2009 at 07:28:03AM +0200, Bas van der Vlies wrote:
> > I knew there is a patch for it, see:
> >   * http://www.mail-archive.com/mauiusers@supercluster.org/msg00321.html
> 
> My manager has asked me to look into the Maui fairshare because when all
> of the active users are over their fairshare their fairshare weighting
> becomes equal.  He said it quite well:
> 
> On Fri, Mar 27, 2009 at 10:26:36AM -0400, Chip Watson wrote:
> > Michael,
> >
> > Maui has the following known bug:
> >
> > If all projects that have pending jobs are over their fairshare, and
> > the other projects are not being used, then Maui takes the unused
> > fairshare and divides it EQUALLY among all projects. It does NOT
> > divide it up in proportion to the other projects fairshare. E.g.
> > Project A share is 80, B is 19, C is 1. A goes inactive, and so the 80
> > is split equally between B and C. So B ends up with 59, and C with 41,
> > changing the ratio between B and C from 19:1 to 3:2.
> >
> > What I'm wondering now is if the job soft limit is also subverted by
> > this non-fairshare of unused fairshare. In other words, soft limit is
> > only imposed if there is no one ready to run who is below their quota.
> >
> > Can you dig into the source code to figure this out?
> 
> In looking at the code in MPriority.c, MFS.c, and MQueue.c, I found
> that the fairshare code was a) being clamped to 0 if negative and
> b) the tools like diagnose -p do not show the actual values of the
> priority (they report negative numbers when they are never used). Also,
> the priorities go from doubles, to longs, to ints, which could cause
> problems as well.
> 
> We run a slightly older version of Maui, and if these issues has been
> fixed, I would immediately upgrade.

REJECTNEGPRIOJOBS       FALSE
ENABLENEGJOBPRIORITY    TRUE

is what you want. Not sure in which version they showed up but at least
from 3.2.6p12

-- 
Ake Sandgren, HPC2N, Umea University, S-90187 Umea, Sweden
Internet: ake at hpc2n.umu.se   Phone: +46 90 7866134 Fax: +46 90 7866126
Mobile: +46 70 7716134 WWW: http://www.hpc2n.umu.se



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