From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vince Weaver <vincent.weaver@maine.edu>
Subject: Re: How to sample memory usage cheaply?
Date: Sat, 1 Apr 2017 09:54:02 -0400 (EDT)
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References: <20170330200404.GA1915@localhost> <2288291.HPAjuFhd8F@agathebauer> <20170401074112.GA8989@localhost>
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To: Benjamin King <benjaminking@web.de>
Cc: Milian Wolff <milian.wolff@kdab.com>, linux-perf-users@vger.kernel.org


On Sat, 1 Apr 2017, Benjamin King wrote:
> Also, the 'perf stat' output that I sent does not make much sense to me right
> now. For example, when I add MAP_POPULATE to the flags for mmap, I only see
> ~40 minor page faults, which I do not understand at all.

have you tried accessing your file in random order?  I think the kernel is 
likely doing some sort of readahead/prefetching.  I think you can change 
that behavior with the madvise() syscall

Vince