linux-kernel - Re: [RFC 4/4] mm: show number of vmalloc pages in /proc/meminfo

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Message-ID: <20181214182904.GE10600@bombadil.infradead.org>
Date:   Fri, 14 Dec 2018 10:29:04 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Roman Gushchin <guroan@...il.com>
Cc:     linux-mm@...ck.org, Alexey Dobriyan <adobriyan@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        kernel-team@...com, Roman Gushchin <guro@...com>
Subject: Re: [RFC 4/4] mm: show number of vmalloc pages in /proc/meminfo

On Fri, Dec 14, 2018 at 10:07:20AM -0800, Roman Gushchin wrote:
> Vmalloc() is getting more and more used these days (kernel stacks,
> bpf and percpu allocator are new top users), and the total %
> of memory consumed by vmalloc() can be pretty significant
> and changes dynamically.
> 
> /proc/meminfo is the best place to display this information:
> its top goal is to show top consumers of the memory.
> 
> Since the VmallocUsed field in /proc/meminfo is not in use
> for quite a long time (it has been defined to 0 by the
> commit a5ad88ce8c7f ("mm: get rid of 'vmalloc_info' from
> /proc/meminfo")), let's reuse it for showing the actual
> physical memory consumption of vmalloc().

Do you see significant contention on nr_vmalloc_pages?  Also, if it's
just an atomic_long_t, is it worth having an accessor for it?  And if
it is worth having an accessor for it, then it can be static.

Also, I seem to be missing 3/4.