From: David Gibson <david@gibson.dropbear.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: qemu-ppc@nongnu.org, agraf@suse.de, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 4/6] pseries: Move hash page table allocation to reset time
Date: Tue, 9 Feb 2016 09:30:04 +1000 [thread overview]
Message-ID: <20160208233004.GA29288@voom.bne.redhat.com> (raw)
In-Reply-To: <56B81D22.7080908@ozlabs.ru>
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On Mon, Feb 08, 2016 at 03:44:18PM +1100, Alexey Kardashevskiy wrote:
> On 02/05/2016 01:13 PM, David Gibson wrote:
> >At the moment the size of the hash page table (HPT) is fixed based on the
> >maximum memory allowed to the guest. As such, we allocate the table during
> >machine construction, and just clear it at reset.
> >
> >However, we're planning to implement a PAPR extension allowing the hash
> >page table to be resized at runtime. This will mean that on reset we want
> >to revert it to the default size. It also means that when migrating, we
> >need to make sure the destination allocates an HPT of size matching the
> >host, since the guest could have changed it before the migration.
> >
> >This patch replaces the spapr_alloc_htab() and spapr_reset_htab() functions
> >with a new spapr_reallocate_hpt() function. This is called at reset and
> >inbound migration only, not during machine init any more.
>
>
> I'd suggest splitting this patch in two (move spapr_hpt_shift_for_ramsize to
> a new patch, or reorganizing it somehow (move spapr_hpt_shift_for_ramsize to
> a different place) - this one is really hard to read and make sure that
> nothing is lost.
Good idea, I'll do that.
> >In addition, we add a new helper to compute the recommended hash table size
> >for a given RAM size. We export this as well as spapr_reallocate_hpt(),
> >since we'll be needing them elsewhere in future.
>
> Do you already have a patch in your queue to exploit this?
>
> I was told few times to export stuff when I have to...
True, I'll look at that again.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2016-02-09 0:00 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-05 2:13 [Qemu-devel] [PATCH 0/6] Cleanups to Hash Page Table handling David Gibson
2016-02-05 2:13 ` [Qemu-devel] [PATCH 1/6] target-ppc: Remove unused kvmppc_update_sdr1() stub David Gibson
2016-02-08 5:39 ` Alexey Kardashevskiy
2016-02-05 2:13 ` [Qemu-devel] [PATCH 2/6] target-ppc: Include missing MMU models for SDR1 in info registers David Gibson
2016-02-08 5:39 ` Alexey Kardashevskiy
2016-02-05 2:13 ` [Qemu-devel] [PATCH 3/6] pseries: Simplify handling of the hash page table fd David Gibson
2016-02-08 6:20 ` Alexey Kardashevskiy
2016-02-05 2:13 ` [Qemu-devel] [PATCH 4/6] pseries: Move hash page table allocation to reset time David Gibson
2016-02-08 4:44 ` Alexey Kardashevskiy
2016-02-08 23:30 ` David Gibson [this message]
2016-02-05 2:13 ` [Qemu-devel] [PATCH 5/6] target-ppc: Remove hack for ppc_hash64_load_hpte*() with HV KVM David Gibson
2016-02-08 6:35 ` Alexey Kardashevskiy
2016-02-05 2:13 ` [Qemu-devel] [PATCH 6/6] target-ppc: Add helpers for updating a CPU's SDR1 and external HPT David Gibson
2016-02-08 5:07 ` Alexey Kardashevskiy
2016-02-08 5:11 ` Alexey Kardashevskiy
2016-02-08 23:34 ` David Gibson
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