linux-kernel - Re: [PATCH 0/2] fs, proc: optimize smaps output formatting

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Message-ID: <1471637924.3893.48.camel@perches.com>
Date:   Fri, 19 Aug 2016 13:18:44 -0700
From:   Joe Perches <joe@...ches.com>
To:     Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Jann Horn <jann@...jh.net>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] fs, proc: optimize smaps output formatting

On Fri, 2016-08-19 at 10:43 -0700, Joe Perches wrote:
> And this would definitely be faster if seq_has_overflowed() was
> used somewhere in the iteration loop.

Adding a seq_has_overflowed() test seems unnecessary as the
fs/seq_file.c traverse() static function already does a
seq_has_overflowed().

And I get:

$ t_mm (your allocate all vma program modified to show count)
count: 65514 pid:2051
$ wc -c /proc/2051/smaps 
39515615 /proc/2051/smaps

smap vma output is a little more than 600 bytes per vma.

I'll look around to see how best go use single_open_size
assuming 768 bytes/vma rounded up to the next PAGE_SIZE.