[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <1160574913.3000.378.camel@laptopd505.fenrus.org>
Date: Wed, 11 Oct 2006 15:55:13 +0200
From: Arjan van de Ven <arjan@...radead.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
"Chen, Kenneth W" <kenneth.w.chen@...el.com>, linux-mm@...ck.org,
Nick Piggin <npiggin@...e.de>
Subject: Re: RSS accounting (was: Re: 2.6.19-rc1-mm1)
On Wed, 2006-10-11 at 06:07 -0600, Eric W. Biederman wrote:
> Arjan van de Ven <arjan@...radead.org> writes:
>
> > On Tue, 2006-10-10 at 17:54 -0600, Eric W. Biederman wrote:
> >
> >> For processes shared pages are not special.
>
> Actually the above is not quite true you can map a shared page twice
> into the same process but in practice it rarely happens.
yeah I'm entirely fine with ignoring that case (or making the person who
does it pay for it :)
>
> > depends on what question you want to answer with RSS.
> > If the question is "workload working set size" then you are right. If
> > the question is "how much ram does my application cause to be used" the
> > answer is FAR less clear....
>
> There are two basic concerns. How do you keep an application from
> going crazy and trashing the rest of your system? A question on what
> number do you need to implement a resource limit.
yet at the same time if 2 apps mmap a shared file, and app 1 keeps it in
pagecache, it doesn't cause app2 to trash, or rather, it's not like if
app 2 did NOT have the page from that file, the system wouldn't trash.
> > You seem to have an implicit definition on what RSS should mean; but
> > it's implicit. Mind making an explicit definition of what RSS should be
> > in your opinion? I think that's the biggest problem we have right now;
> > several people have different ideas about what it should/could be, and
> > as such we're not talking about the same thing. Lets first agree/specify
> > what it SHOULD mean, and then we can figure out what gets counted for
> > that ;)
>
> Well I tried to defined it in terms of what you can use it for.
>
> I would define the resident set size as the total number of bytes
> of physical RAM that a process (or set of processes) is using,
> irrespective of the rest of the system.
>
>
> So I think the counting should be primarily about what is mapped into
> the page tables. But other things can be added as is appropriate or
> easy.
>
> The practical effect should be that an application that needs more
> pages than it's specified RSS to avoid thrashing should thrash but
> it shouldn't take the rest of the system with it.
so by your definition, hugepages are part of RSS.
Ken: what is your definition of RSS ?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists