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

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Message-ID: <CAM9d7ch=yrF5ej3=ukNZCouq3ddbJ+QNZoeABH+Tm=Lqg0buhw@mail.gmail.com>
Date:	Mon, 16 Mar 2015 17:35:04 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Minchan Kim <minchan@...nel.org>,
	Joonsoo Kim <js1304@...il.com>
Subject: Re: [RFC/PATCHSET 0/6] perf kmem: Implement page allocation analysis (v1)

Hi Ingo,

On Mon, Mar 16, 2015 at 5:26 PM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Namhyung Kim <namhyung@...nel.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
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