[fedora-virt] disabling ksm by default

[Dan Kenigsberg]

On Tue, Oct 27, 2009 at 12:24:13PM +0200, Izik Eidus wrote:
> On 10/27/2009 12:12 PM, Mark McLoughlin wrote:
>> Hi Izik,
>>
>> On Tue, 2009-10-27 at 00:55 +0200, Izik Eidus wrote:
>>    
>>> Hi, I saw that Fedora 12 will have ksm tunning script that control the
>>> ksm speed / kernel pages allocation.
>>>
>>> The only problem that I have is - as far as I remember ksm is by default
>>> enabled and only with 2000 kernel pages...
>>> What I am worried about is that users wont use the ksm tunning script
>>> and would just run ksm with this 2000 kernel pages -
>>> the result would be that ksm will probably merge just the zero pages
>>> (that could be alot of memory) and the user might not know
>>> that much more memory can be saved...
>>>
>>> Is it possible to at least make ksm disabled by default? so the users
>>> will have to run the ksm tunning script when they want to start ksm?
>>>      
>> ksm is disabled by default currently
>>    
>
> Ok so we are fine then.
>

Actually, Izik is refering to the fact that ksm is, by default, running
when the kernel boots.

He'd like to see something like

diff -u -r1.1 linux-2.6-ksm-updates.patch
--- linux-2.6-ksm-updates.patch 7 Aug 2009 19:07:39 -0000       1.1
+++ linux-2.6-ksm-updates.patch 27 Oct 2009 12:34:57 -0000
@@ -1661,7 +1661,7 @@
  #define KSM_RUN_MERGE 1
  #define KSM_RUN_UNMERGE       2
 -static unsigned int ksm_run;
-+static unsigned int ksm_run = KSM_RUN_MERGE;
++static unsigned int ksm_run = KSM_RUN_STOP;
  
  static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait);
  static DEFINE_MUTEX(ksm_thread_mutex);

to behave more like upstream 2.6.32

http://osdir.com/ml/linux-kernel/2009-09/msg09309.html
http://osdir.com/ml/linux-kernel/2009-09/msg09777.html