[jira] [Updated] (YARN-4768) getAvailablePhysicalMemorySize can be inaccurate on linux

["Nathan Roberts (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/YARN-4768?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nathan Roberts updated YARN-4768:
---------------------------------
    Attachment: YARN-4768.patch

Patch for trunk.

Also changed getPhysicalMemorySize() to exclude:
- HardwareCorrupted pages - Not that uncommon.
- HugePagesTotal * hugePageSize - probably not commonly configured on compute nodes but just in case it seems reasonable to not count these.

Comments welcome on alternative ways to approach these.


> getAvailablePhysicalMemorySize can be inaccurate on linux
> ---------------------------------------------------------
>
>                 Key: YARN-4768
>                 URL: https://issues.apache.org/jira/browse/YARN-4768
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: nodemanager
>    Affects Versions: 3.0.0, 2.7.2
>         Environment: Linux
>            Reporter: Nathan Roberts
>            Assignee: Nathan Roberts
>         Attachments: YARN-4768.patch
>
>
> Algorithm currently uses "MemFree" + "Inactive" from /proc/meminfo
> "Inactive" may not be a very good indication of how much memory can be readily freed because it contains both:
> - Pages mapped with MAP_SHARED|MAP_ANONYMOUS (regardless of whether they're being actively accessed or not. Unclear to me why this is the case...)
> - Pages mapped MAP_PRIVATE|MAP_ANONYMOUS that have not been accessed recently
> Both of these types of pages probably shouldn't be considered "Available".
> "Inactive(file)" would seem more accurate but it's not available in all kernel versions. To keep things simple, maybe just use "Inactive(file)" if available, otherwise fallback to "Inactive".



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