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Re: Slow down with: 'Make "info qom-tree" show children sorted'
From: |
David Gibson |
Subject: |
Re: Slow down with: 'Make "info qom-tree" show children sorted' |
Date: |
Mon, 13 Jul 2020 11:13:44 +1000 |
On Tue, 07 Jul 2020 14:00:06 +0200
Markus Armbruster <armbru@redhat.com> wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
>
> > On 07/07/20 07:33, Markus Armbruster wrote:
> >> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> >>
> >>> On 7/7/20 6:45 AM, Thomas Huth wrote:
> >>>> On 27/05/2020 10.47, Markus Armbruster wrote:
> >>>>> "info qom-tree" prints children in unstable order. This is a pain
> >>>>> when diffing output for different versions to find change. Print it
> >>>>> sorted.
> >>>>>
> >>>>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> >>>>> ---
> >>>>> qom/qom-hmp-cmds.c | 24 ++++++++++++++++--------
> >>>>> 1 file changed, 16 insertions(+), 8 deletions(-)
> >>>>
> >>>> Hi Markus,
> >>>>
> >>>> this patch causes a slow down of the qtests which becomes quite massive
> >>>> when e.g. using the ppc64 and thourough testing. When I'm running
> >>>>
> >>>> QTEST_QEMU_BINARY="ppc64-softmmu/qemu-system-ppc64" time \
> >>>> ./tests/qtest/device-introspect-test -m slow | tail -n 10
> >>>>
> >>>> the test runs for ca. 6m40s here before the patch got applied, and for
> >>>> mor than 20 minutes after the patch got applied!
> >>
> >> That's surprising.
> >
> > It's a bit surprising indeed, but on the other hand using
> > g_queue_insert_sorted results in a quadratic loop.
>
> The surprising part is that n turns out to be large enough for n^2 to
> matter *that* much.
Is this another consequence of the ludicrous number of QOM objects we
create for LMB DRCs (one for every 256MiB of guest RAM)? Avoiding that
is on my list. Though avoiding a n^2 behaviour here is probably a good
idea anyway.
--
David Gibson <dgibson@redhat.com>
Principal Software Engineer, Virtualization, Red Hat
pgpb3C_d1xy97.pgp
Description: OpenPGP digital signature
- Slow down with: 'Make "info qom-tree" show children sorted', Thomas Huth, 2020/07/07
- Re: Slow down with: 'Make "info qom-tree" show children sorted', Philippe Mathieu-Daudé, 2020/07/07
- Re: Slow down with: 'Make "info qom-tree" show children sorted', Markus Armbruster, 2020/07/07
- Re: Slow down with: 'Make "info qom-tree" show children sorted', Paolo Bonzini, 2020/07/07
- Re: Slow down with: 'Make "info qom-tree" show children sorted', Markus Armbruster, 2020/07/07
- Re: Slow down with: 'Make "info qom-tree" show children sorted', Daniel P . Berrangé, 2020/07/07
- Re: Slow down with: 'Make "info qom-tree" show children sorted',
David Gibson <=
- Re: Slow down with: 'Make "info qom-tree" show children sorted', Markus Armbruster, 2020/07/13
- Re: Slow down with: 'Make "info qom-tree" show children sorted', David Gibson, 2020/07/15
- Re: Slow down with: 'Make "info qom-tree" show children sorted', Markus Armbruster, 2020/07/16
- Re: Slow down with: 'Make "info qom-tree" show children sorted', David Gibson, 2020/07/17
Re: Slow down with: 'Make "info qom-tree" show children sorted', Daniel P . Berrangé, 2020/07/07
Re: Slow down with: 'Make "info qom-tree" show children sorted', Daniel P . Berrangé, 2020/07/07