linux-kernel - Re: [RFC] perf tools: Add hugetlbfs memory recognition

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Date:	Fri, 3 Jul 2015 12:16:36 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Hou Pengyang <houpengyang@...wei.com>
Cc:	mingo@...hat.com, namhyung@...nel.org, a.p.zijlstra@...llo.nl,
	wangnan0@...wei.com, linux-kernel@...r.kernel.org,
	zhu.wen-jie@...com
Subject: Re: [RFC] perf tools: Add hugetlbfs memory recognition

Em Fri, Jul 03, 2015 at 06:21:48PM +0800, Hou Pengyang escreveu:
> On 2015/6/30 22:50, Arnaldo Carvalho de Melo wrote:
> >Well, we _can_ detect this automatically, its just a matter of parsing
> >/proc/PID/smaps, right?

<SNIP>

> >What I was discussing was a way only parse smaps when we know we need
> >to, i.e. when we, for instance, parsing /proc/PID/maps, find a map that
> >we think may be a hugetlb one, maybe some other way to tell us that
> >hugetlb maps are in place, looking at the hugetlbfs stats somehow?

<SNIP>

> from /proc/self/mounts, we can get mount point of hugetlbfs.
> in my system, it is "/mnt/huge". So that, when mmap2 event
> comes from userspace, we can compare prefix of filename with
> hugetlbfs mount point (e.g "/mnt/huge") to check if it is a
> file in hugetlbfs. if it is, set MAP_HUGELTB, otherwise, not set.
 
> There is no need to parse /proc/PID/smaps now, what's more,
> it is not difficult to parse "/proc/self/mounts".

A-ha! please take a look at using the find_mountpoint() function
in tools/lib/api/fs/, I guess that should be enough for you?

- Arnaldo
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