ksmd - what is expected behavior?

[Tom London]

On Tue, Oct 27, 2009 at 8:59 AM, Mark McLoughlin <markmc at redhat.com> wrote:
> Hi Tom,
>
> On Tue, 2009-10-27 at 08:58 -0700, Tom London wrote:
>> I'm running Rawhide with a qemu-kvm VM that runs WinXP.
>>
>> I'm noticing 'ksmd' running at a constant 15-25% of my cpu, for example:
>>
>>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>>    32 root      25   5     0    0    0 S 21.2  0.0   2:06.75 ksmd
>>  2265 tbl       20   0 1227m 530m 8256 R 17.2 13.5   3:09.05 qemu-kvm
>>  1599 root      20   0  220m  42m  17m S  5.3  1.1   0:55.02 Xorg
>>  2203 tbl       20   0 1234m  62m  24m S  5.0  1.6   0:28.93 rhythmbox
>>
>> Checking, I see that "ksmd" is running, but "ksmtuned" is not.
>>
>> System is Thinkpad X200 with 4GB RAM.  VM image is configured at 512MB.
>>
>> Is this "to be expected" behavior?
>
> We're just discussing something similar on the fedora-virt list
>
> Currently, ksm is enabled by default in the kernel - since it's disabled
> by default in 2.6.32, we'll probably switch to that behaviour
>
> Do you have the ksm or ksmtuned init scripts enabled? Does enabling
> ksmtuned help reduce the CPU usage?
>
> Cheers,
> Mark.
>
Appears that Rawhide has "ksmd" enabled by default.  "ksmtuned" is not
enabled by default.

Starting ksmtuned via
[root at tlondon init.d]# service ksmtuned start
Starting ksmtuned:                                         [  OK  ]
[root at tlondon init.d]#

Had no immediate effect (in fact, appeared to increase CPU up to about
28-30%) for about a minute or 2.

But after that, top no longer reports ksmd:

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 2265 tbl       20   0 1227m 530m 8256 S 17.2 13.5   6:04.56 qemu-kvm
 2298 tbl       20   0  849m 161m  27m S 13.2  4.1   1:18.68 firefox
 1599 root      20   0  219m  44m  17m S  9.3  1.1   1:28.51 Xorg
 2203 tbl       20   0 1235m  64m  24m S  4.0  1.6   0:53.86 rhythmbox
 1903 tbl        9 -11  541m  29m  28m S  3.0  0.8   0:23.55 pulseaudio

But I notice that "ksm" appears off:

[root at tlondon init.d]# service ksm status
ksm is not running
[root at tlondon init.d]# service ksmtuned status
ksmtuned (pid  2559) is running...
[root at tlondon init.d]#

Interesting tuning.... ;)

Any idea what is going on?

tom
-- 
Tom London