[lxc-devel] Kernel Samepage Merging

[Guido Trotter]

On Mon, Feb 7, 2011 at 9:04 PM, Daniel Lezcano <daniel.lezcano at free.fr> wrote:
> On 02/07/2011 08:19 PM, richard -rw- weinberger wrote:
>> Hi,
>>
>> Can KSM (http://lwn.net/Articles/306704/) help LXC?
>> I guess there are a lot of identical pages when logs of containers are running.
>
> Yes, absolutely. As it is very CPU consuming that should be optional.
> I looked at it last year but I have no idea on how to use the madvice
> syscall ...
> Hints are welcome :)

Well, using it is easy, the problem is in this case it's not LXC who
allocates the memory (and could then madvice about it), but the
processes inside the container.
And it would be wrong for things like syslog to run it "generically"
(as on a single host system the hint would be wrong).
I guess one way would be patching the various deamons to do it in a
configurable way, the other one to ask the container people to add an
option to make sure that memory allocated by processes (or only
certain processes) in a container is automatically marked as
mergeable.
Or that you can edit some other process' memory via /sys or /cgroups
value changes. Perhaps we can bring this to discussion with the kernel
people and ask for their thoughts?

Thanks,

Guido