Re: [PATCH V3] KSM: allow dedup all tasks memory

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Hi.

ksm by default working only on memory that added by
madvise().

And only way get that work on other applications:
  * Use LD_PRELOAD and libraries
  * Patch kernel

Lets use kernel task list and add logic to import VMAs from tasks.

That behaviour controlled by new attributes:
  * mode:
    I try mimic hugepages attribute, so mode have two states:
      * madvise      - old default behaviour
      * always [new] - allow ksm to get tasks vma and
                       try working on that.
  * seeker_sleep_millisecs:
    Add pauses between imports tasks VMA

For rate limiting proporses and tasklist locking time,
ksm seeker thread only import VMAs from one task per loop.

Some numbers from different not madvised workloads.
Formulas:
  Percentage ratio = (pages_sharing - pages_shared)/pages_unshared
  Memory saved = (pages_sharing - pages_shared)*4/1024 MiB
  Memory used = free -h

  * Name: My working laptop
    Description: Many different chrome/electron apps + KDE
    Ratio: 5%
    Saved: ~100  MiB
    Used:  ~2000 MiB

  * Name: K8s test VM
    Description: Some small random running docker images
    Ratio: 40%
    Saved: ~160 MiB
    Used:  ~920 MiB

  * Name: Ceph test VM
    Description: Ceph Mon/OSD, some containers
    Ratio: 20%
    Saved: ~60 MiB
    Used:  ~600 MiB

  * Name: BareMetal K8s backend server
    Description: Different server apps in containers C, Java, GO & etc
    Ratio: 72%
    Saved: ~5800 MiB
    Used:  ~35.7 GiB

  * Name: BareMetal K8s processing server
    Description: Many instance of one CPU intensive application
    Ratio: 55%
    Saved: ~2600 MiB
    Used:  ~28.0 GiB

  * Name: BareMetal Ceph node
    Description: Only OSD storage daemons running
    Raio: 2%
    Saved: ~190 MiB
    Used:  ~11.7 GiB

Out of curiosity, have you compared these results with UKSM [1]?

Thanks.

--
  Oleksandr Natalenko (post-factum)

[1] https://github.com/dolohow/uksm



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