KSM not working on 2.6.28.7 and qemu-kvm 0.12.2 ?

DISCUSSION Nikola Ciprich 2 participants 3 messages Feb 22, 2010 – Feb 23, 2010 1 message not in the archive KVM

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Nikola Ciprich

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2010-02-22 05:40 UTC #1 lore raw

In reply to a message not in the archive

Hi Gilles, maybe You have the same problem I experienced? see http://www.mail-archive.com/[email protected]/msg28572.html
nik

Quoted 49 lines · Gilles PIETRI

Hi,
I'm running a 2.6.32.7 kernel with KSM enabled (CONFIG_KSM=y), with qemu-kvm 0.12.2 that has support for KSM (exec.c checks for MADV_MERGEABLE)..
So I have KSM running, /sys/kernel/mm/ksm/run is at 1, and after a few hours running a dozen of VMs, many of them running the same OS/base image, I see no page being shared, KSM seems inactive.
Values are pretty much to their default value, and it seems KSM is simply not working.. I see ksmd in the process list though, but here are the sysfs values reported:
==> /sys/kernel/mm/ksm/full_scans <==
0
==> /sys/kernel/mm/ksm/max_kernel_pages <==
1027257
==> /sys/kernel/mm/ksm/pages_shared <==
0
==> /sys/kernel/mm/ksm/pages_sharing <==
0
==> /sys/kernel/mm/ksm/pages_to_scan <==
100
==> /sys/kernel/mm/ksm/pages_unshared <==
0
==> /sys/kernel/mm/ksm/pages_volatile <==
0
==> /sys/kernel/mm/ksm/run <==
1
==> /sys/kernel/mm/ksm/sleep_millisecs <==
20
Any clues?
Cheers,
Gilou
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Signature · 13 lines

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Ing. Nikola CIPRICH
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Gilles PIETRI

2010-02-22 21:02 UTC #2 lore raw

Quoted 4 lines · Nikola Ciprich

Hi Gilles, maybe You have the same problem I experienced? see http://www.mail-archive.com/[email protected]/msg28572.html
nik

Hi,

The linux headers do include the MADV_MERGEABLE settings, and the libc is the debian one which happened to work fine earlier in this regard. Anyway I still added the flags just to make sure, and nothing more happens.

Cheers,

Gilou

Quoted 51 lines · Gilles PIETRI

Quoted 49 lines
Hi,
I'm running a 2.6.32.7 kernel with KSM enabled (CONFIG_KSM=y), with qemu-kvm 0.12.2 that has support for KSM (exec.c checks for MADV_MERGEABLE)..
So I have KSM running, /sys/kernel/mm/ksm/run is at 1, and after a few hours running a dozen of VMs, many of them running the same OS/base image, I see no page being shared, KSM seems inactive.
Values are pretty much to their default value, and it seems KSM is simply not working.. I see ksmd in the process list though, but here are the sysfs values reported:
==> /sys/kernel/mm/ksm/full_scans <==
0
==> /sys/kernel/mm/ksm/max_kernel_pages <==
1027257
==> /sys/kernel/mm/ksm/pages_shared <==
0
==> /sys/kernel/mm/ksm/pages_sharing <==
0
==> /sys/kernel/mm/ksm/pages_to_scan <==
100
==> /sys/kernel/mm/ksm/pages_unshared <==
0
==> /sys/kernel/mm/ksm/pages_volatile <==
0
==> /sys/kernel/mm/ksm/run <==
1
==> /sys/kernel/mm/ksm/sleep_millisecs <==
20
Any clues?
Cheers,
Gilou
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Gilles PIETRI

2010-02-23 18:22 UTC #3 lore raw

Quoted 6 lines · Gilles PIETRI

Quoted 4 lines · Nikola Ciprich
Hi Gilles, maybe You have the same problem I experienced? see http://www.mail-archive.com/[email protected]/msg28572.html
nik

Quoted 7 lines

Hi,
The linux headers do include the MADV_MERGEABLE settings, and the libc is the debian one which happened to work fine earlier in this regard. Anyway I still added the flags just to make sure, and nothing more happens.
Cheers,
Gilou

OK, I had a doubt, so I did it again, and made sure there wasn't a chance for the MADV_* to be missing... And it was the issue actually.. Not sure what happened there, given the linux headers are here.. It works fine finally, thanks Nikola for your pointer.

Regards,

Gilou

Quoted 54 lines

Quoted 52 lines · Gilles PIETRI
Quoted 49 lines
Hi,
I'm running a 2.6.32.7 kernel with KSM enabled (CONFIG_KSM=y), with qemu-kvm 0.12.2 that has support for KSM (exec.c checks for MADV_MERGEABLE)..
So I have KSM running, /sys/kernel/mm/ksm/run is at 1, and after a few hours running a dozen of VMs, many of them running the same OS/base image, I see no page being shared, KSM seems inactive.
Values are pretty much to their default value, and it seems KSM is simply not working.. I see ksmd in the process list though, but here are the sysfs values reported:
==> /sys/kernel/mm/ksm/full_scans <==
0
==> /sys/kernel/mm/ksm/max_kernel_pages <==
1027257
==> /sys/kernel/mm/ksm/pages_shared <==
0
==> /sys/kernel/mm/ksm/pages_sharing <==
0
==> /sys/kernel/mm/ksm/pages_to_scan <==
100
==> /sys/kernel/mm/ksm/pages_unshared <==
0
==> /sys/kernel/mm/ksm/pages_volatile <==
0
==> /sys/kernel/mm/ksm/run <==
1
==> /sys/kernel/mm/ksm/sleep_millisecs <==
20
Any clues?
Cheers,
Gilou
Signature · 3 lines
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