Re: [RFC/PATCHSET 0/6] perf kmem: Implement page allocation analysis (v1)

Namhyung Kim
2015-03-16T08:35:30Z

Hi Ingo,

On Mon, Mar 16, 2015 at 5:26 PM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Namhyung Kim <namhyung@kernel.org> wrote:
>
>> On Thu, Mar 12, 2015 at 11:58:37PM +0900, Namhyung Kim wrote:
>> > On Thu, Mar 12, 2015 at 11:41:19AM +0100, Ingo Molnar wrote:
>> > > So there's one thing that would be useful: to track pages allocated on
>> > > one node, but freed on another. Those kinds of allocation/free
>> > > patterns are especially expensive and might make sense to visualize.
>> >
>> > I think it can be done easily as slab analysis already contains the info.
>>
>> Hmm.. it seems slab events provide the node info but page events
>> don't. Without it, I don't know which node a page is in so cannot
>> determine such cross-node alloc+free patterns.
>
> Well, but we know the CPU that the allocation occured on, and can map
> the CPU to the node.

Does it gaurantee that the page always belongs to a same node
allocating cpu is in? I can simply map the page with an node using
cpu info but was not sure whether that's always correct.

Thanks,
Namhyung