linux-kernel - Re: get_vmalloc_info() and /proc/meminfo insanely expensive

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Message-ID: <alpine.DEB.2.10.1508131249050.14178@chino.kir.corp.google.com>
Date:	Thu, 13 Aug 2015 12:50:13 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: get_vmalloc_info() and /proc/meminfo insanely expensive

On Thu, 13 Aug 2015, Linus Torvalds wrote:

> On Thu, Aug 13, 2015 at 11:32 AM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > Here's a totally untested patch (I'll reboot and test soon - it does
> > at least compile for me).
> 
> Seems to work for me. Anybody want to object to the admittedly disgusting patch?
> 

Rather than a time based approach, why not invalidate when it is known to 
change, either on the next call to get_vmalloc_info() or as part of the 
vmalloc operation itself?  If the numbers don't change during your test, 
this would seem better and I don't think any vmalloc() function is 
intended to be hot.
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