Re: [PATCH v1][RFC] drivers/xen, balloon driver numa support in kernel

From: Konrad Rzeszutek Wilk
Date: Tue Aug 13 2013 - 08:46:51 EST


On Mon, Aug 12, 2013 at 4:26 PM, Dario Faggioli
<dario.faggioli@xxxxxxxxxx> wrote:
> Hi Yechen.
>
> Thanks for doing and sharing this part of the thing too.
>
> See what I already told you on xen-devel about Cc-ing the relevant
> people. For Linux as well, you can check at the MAINTAINERS file. This
> exact thing (i.e., who the actual maintainers are) is changing a bit
> right in these days... See this commit:
>
> http://git.kernel.org/cgit/linux/kernel/git/xen/tip.git/commit/?h=devel/for-jens-3.12&id=3eeef8f72a9365fe20f2c9d84b0afe60a20788cd
>
> On lun, 2013-08-12 at 22:13 +0800, Yechen Li wrote:
>> This small patch adds numa support for balloon driver. Kernel version: 3.11-rc5
>>
> Mmm... Is that the case? I tried to apply it there and I have one failed
> hunk (#12). Anyway, could you please rebase it on the tip of some
> relevant git tree?
>
> Linus' tree would be fine, I guess:
>
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git
>
> However, since these kind of patches should probably go through Konrad's
> (or other Linux Xen maintainers) tree anyway, you could well base on top
> of:
>
> http://git.kernel.org/cgit/linux/kernel/git/konrad/xen.git/
>
> Or perhaps on some branch of this one here:
>
> http://git.kernel.org/cgit/linux/kernel/git/xen/tip.git/
>
> Konrad, David, would you find 5 minutes to explain Yechen which tree and
> which branch he should use, or point him to the appropriate
> documentation for understanding that? Thanks...

I would suggest he base it on top of devel/for-linus-3.12 for right now. That
branch will become 'stable/for-linus-3.12' which is then going to be
sent to Linus
for v3.12 merge window.

Obviously the patches will need to be reviewed before they go in.
>
>> It's just a RFC version, since I'm waiting for the interface of numa topology.
>> The balloon driver will read arguments from xenstore: /local/domain/(id)/memory
>> /target_nid, and settle the memory increase/decrease operation on specified
>> p-nodeID.
>> To achieve this, I expand the page-list: ballooned_pages to an array:
>> ballooned_pages[MAX_BALLOONNODES], so that balloon can distinguish pages from
>> different node.
>> For the guest without numa, this MAX_BALLOONNODES = 1 so that the balloon falls
>> back to a no-numa version.
>>

You also need to be backwards compatible in case those keys don't exist, or not
all of them exist. Or they have bogus values.
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