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Posted to issues@mesos.apache.org by "James Peach (JIRA)" <ji...@apache.org> on 2015/12/07 17:55:10 UTC

[jira] [Commented] (MESOS-3997) Switch to fixed-point for resources

    [ https://issues.apache.org/jira/browse/MESOS-3997?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15045227#comment-15045227 ] 

James Peach commented on MESOS-3997:
------------------------------------

I believe that MESOS-4071 is another manifestation of this problem. In that issue, we subtract the CPU resource from both the roles' allocation and the slave total resources. One of the subtractions goes to zero and the other goes to an extremely small fraction (3.3389957465601583e-14) of a CPU.

> Switch to fixed-point for resources
> -----------------------------------
>
>                 Key: MESOS-3997
>                 URL: https://issues.apache.org/jira/browse/MESOS-3997
>             Project: Mesos
>          Issue Type: Improvement
>          Components: allocation, master
>            Reporter: Neil Conway
>              Labels: mesosphere, resources
>
> Using floating point for resources is problematic, because roundoff and precision errors when doing resource math can produce unexpected results.
> Instead, we should probably adopt a fixed-point representation: e.g., CPU resources will be measured as an integer number of fractional CPUs (e.g., 25 deci-CPUs == 2.5 CPUs).



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