From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 2/3] KVM: Guest page hinting functionality
Date: Wed, 02 Aug 2017 15:20:46 -0400
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Cc: kvm@vger.kernel.org, mst@redhat.com, david@redhat.com,
        yang.zhang.wz@gmail.com, wei.w.wang@intel.com
To: Nitesh Narayan Lal <nilal@redhat.com>,
        Pankaj Gupta <pagupta@redhat.com>
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On Wed, 2017-08-02 at 14:59 -0400, Nitesh Narayan Lal wrote:
>=20
> > > -struct hypervisor_pages hypervisor_pagelist[MAX_FGPT_ENTRIES];
> > > +struct hypervisor_pages hypervisor_pagelist[MAX_FGPT_ENTRIES -
> > > 1];
> > > +
> > > +static void empty_hyperlist(void)
> > > +{
> > > +	int i =3D 0;
> > > +
> > > +	while (i < MAX_FGPT_ENTRIES - 1) {
> >=20
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0MAX_FGPT_ENTRIES in-place of 'MAX_F=
GPT_ENTRIES - 1' here
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0and at similar other places?
>=20
> This is because CPU local list has a total of 1000 entries
> (MAX_FGPT_ENTRIES) where as CPU global list has 999 entries. If you
> see
> the arch_free_page_slowpath() and consider a situation where there
> are
> 1000 entries of singly allocated free pages in cpu-local list i.e.,
> none
> of them are re-allocated. While adding them to the cpu global list
> when
> cpu local list index reaches to 1000 the outer loop will terminate
> due
> to which cpu global list index will never reach to 1000 and
> compress_hyperlist()/make_hypercall() will never be called.
> >=20
>=20
Can you explain why the hypervisor_pagelist
is smaller than the cpu local list?

This makes no sense to me. Why are they not
the same size?

That would certainly make the code easier to read.

--=20
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