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Tue, 7 Jul 2020 12:04:51 +0000 (UTC) Date: Tue, 7 Jul 2020 13:04:49 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Subject: Re: Slow down with: 'Make "info qom-tree" show children sorted' Message-ID: <20200707120449.GJ2649462@redhat.com> References: <20200527084754.7531-1-armbru@redhat.com> <20200527084754.7531-3-armbru@redhat.com> <49bea110-0a3d-5a40-6647-67b116fb41b5@redhat.com> <5e967e5f-8ae5-01cc-0dfe-f22e0f03b6b3@redhat.com> <87y2nvanya.fsf@dusky.pond.sub.org> <794f6901-5fe3-f7a1-45e7-f277f687cb6b@redhat.com> <87v9iz7cxl.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87v9iz7cxl.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.14.3 (2020-06-14) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/07 00:31:00 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Laurent Vivier , Thomas Huth , ehabkost@redhat.com, Alex =?utf-8?Q?Benn=C3=A9e?= , mark.cave-ayland@ilande.co.uk, qemu-devel@nongnu.org, Greg Kurz , =?utf-8?Q?C=C3=A9dric?= Le Goater , David Gibson , Paolo Bonzini , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Jul 07, 2020 at 02:00:06PM +0200, Markus Armbruster wrote: > Paolo Bonzini writes: > > > On 07/07/20 07:33, Markus Armbruster wrote: > >> Philippe Mathieu-Daudé 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 > >>>>> --- > >>>>> 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. The test suite as a whole is more like n^3 because it is running sooooo many repeats of "info qom-tree" Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|