linux-kernel - Re: [RFC][Patch v8 6/7] KVM: Enables the kernel to isolate and report free pages

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Message-ID: <20190208163601-mutt-send-email-mst@kernel.org>
Date:   Fri, 8 Feb 2019 16:38:09 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Nitesh Narayan Lal <nitesh@...hat.com>
Cc:     Alexander Duyck <alexander.duyck@...il.com>,
        kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.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>, david@...hat.com,
        dodgen@...gle.com, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        dhildenb@...hat.com, Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [RFC][Patch v8 6/7] KVM: Enables the kernel to isolate and
 report free pages

On Fri, Feb 08, 2019 at 03:41:55PM -0500, Nitesh Narayan Lal wrote:
> >> I am also planning to try Michael's suggestion of using MAX_ORDER - 1.
> >> However I am still thinking about a workload which I can use to test its
> >> effectiveness.
> > You might want to look at doing something like min(MAX_ORDER - 1,
> > HUGETLB_PAGE_ORDER). I know for x86 a 2MB page is the upper limit for
> > THP which is the most likely to be used page size with the guest.
> Sure, thanks for the suggestion.

Given current hinting in balloon is MAX_ORDER I'd say
share code. If you feel a need to adjust down the road,
adjust both of them with actual testing showing gains.

-- 
MST