Re: [PATCH 3/3 v3] mm/vmalloc: Cache the vmalloc memory info

From: Ingo Molnar
Date: Mon Aug 24 2015 - 03:00:12 EST



* Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> wrote:

> I was curious why these fields were ever added to /proc/meminfo, and dug
> up this:
>
> commit d262ee3ee6ba4f5f6125571d93d9d63191d2ef76
> Author: Andrew Morton <akpm@xxxxxxxxx>
> Date: Sat Apr 12 12:59:04 2003 -0700
>
> [PATCH] vmalloc stats in /proc/meminfo
>
> From: Matt Porter <porter@xxxxxxx>
>
> There was a thread a while back on lkml where Dave Hansen proposed this
> simple vmalloc usage reporting patch. The thread pretty much died out as
> most people seemed focused on what VM loading type bugs it could solve. I
> had posted that this type of information was really valuable in debugging
> embedded Linux board ports. A common example is where people do arch
> specific setup that limits there vmalloc space and then they find modules
> won't load. ;) Having the Vmalloc* info readily available is real useful in
> helping folks to fix their kernel ports.
>
> That thread is at <http://thread.gmane.org/gmane.linux.kernel/53360>.
>
> [Maybe one could just remove the fields and see if anybody actually
> notices/cares any longer. Or, if they are only used by kernel
> developers, put them in their own file.]

So instead of removing the fields (which I'm quite sure is an ABI breaker as it
could break less robust /proc/meminfo parsers and scripts), we could just report
'0' all the time - and have the real info somewhere else?

Thanks,

Ingo
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