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

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Date:   Thu, 4 Apr 2019 09:28:38 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Nitesh Narayan Lal <nitesh@...hat.com>,
        kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Paolo Bonzini <pbonzini@...hat.com>, lcapitulino@...hat.com,
        pagupta@...hat.com, wei.w.wang@...el.com,
        Yang Zhang <yang.zhang.wz@...il.com>,
        Rik van Riel <riel@...riel.com>, dodgen@...gle.com,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        dhildenb@...hat.com, Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: On guest free page hinting and OOM

On Tue, Apr 02, 2019 at 04:43:03PM -0700, Alexander Duyck wrote:
> Yes, but hopefully it should be a small enough amount that nobody will
> notice. In many cases devices such as NICs can consume much more than
> this regularly for just their Rx buffers and it is not an issue. There
> has to be a certain amount of overhead that any given device is
> allowed to consume. If we contain the balloon hinting to just 64M that
> should be a small enough amount that nobody would notice in practice.

I am still inclined to add ability for balloon to exit to host on OOM
if any hints are outstanding.

If nothing else will be helpful for stats.

-- 
MST