linux-kernel - Re: On guest free page hinting and OOM

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Message-ID: <20190401104608-mutt-send-email-mst@kernel.org>
Date:   Mon, 1 Apr 2019 10:47:56 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     Nitesh Narayan Lal <nitesh@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        pbonzini@...hat.com, lcapitulino@...hat.com, pagupta@...hat.com,
        wei.w.wang@...el.com, yang.zhang.wz@...il.com, riel@...riel.com,
        dodgen@...gle.com, konrad.wilk@...cle.com, dhildenb@...hat.com,
        aarcange@...hat.com, alexander.duyck@...il.com
Subject: Re: On guest free page hinting and OOM

On Mon, Apr 01, 2019 at 04:11:42PM +0200, David Hildenbrand wrote:
> > The interesting thing is most probably: Will the hinting size usually be
> > reasonable small? At least I guess a guest with 4TB of RAM will not
> > suddenly get a hinting size of hundreds of GB. Most probably also only
> > something in the range of 1GB. But this is an interesting question to
> > look into.
> > 
> > Also, if the admin does not care about performance implications when
> > already close to hinting, no need to add the additional 1Gb to the ram size.
> 
> "close to OOM" is what I meant.

Problem is, host admin is the one adding memory. Guest admin is
the one that knows about performance.

> 
> -- 
> 
> Thanks,
> 
> David / dhildenb