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From: David Gibson <dgibson@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: "Laurent Vivier" <lvivier@redhat.com>,
	"Thomas Huth" <thuth@redhat.com>,
	berrange@redhat.com, ehabkost@redhat.com,
	"Alex Bennée" <alex.bennee@linaro.org>,
	mark.cave-ayland@ilande.co.uk, qemu-devel@nongnu.org,
	"Greg Kurz" <groug@kaod.org>, "Cédric Le Goater" <clg@kaod.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: Re: Slow down with: 'Make "info qom-tree" show children sorted'
Date: Fri, 17 Jul 2020 16:00:45 +1000	[thread overview]
Message-ID: <20200717160045.5ea0773d@umbus.fritz.box> (raw)
In-Reply-To: <87a700rpf6.fsf@dusky.pond.sub.org>

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On Thu, 16 Jul 2020 07:37:17 +0200
Markus Armbruster <armbru@redhat.com> wrote:

> David Gibson <dgibson@redhat.com> writes:
> 
>  [...]  
>  [...]  
>  [...]  
>  [...]  
>  [...]  
>  [...]  
>  [...]  
>  [...]  
>  [...]  
> >
> > ... as you say, 256 shouldn't really be a problem.  I was concerned
> > about LMB DRCs rather than PCI DRCs.  To have that show up, you might
> > need to create a machine with a large difference between initial memory
> > and maxmem - I think you'll get a DRC object for every 256MiB in there,
> > which can easily get into the thousands for large (potential) memory
> > VMs.  
> 
> Okay, I can reproduce: with -m 256,128G, /machine has 549 children, of
> which 511 are spapr-drc-lmb.

Ok.

> > I don't know what the config was that showed up this problem in the
> > first place, and whether that could be the case there.  
> 
> Thomas reported device-introspect-test -m slow has become much slower
> for ppc64.  Bisection traced it to my commit e8c9e65816 "qom: Make "info
> qom-tree" show children sorted".  Uses default memory size, no
> spapr-drc-lmb as far as I remember.

Ok, I think that nixes my theory.

> >> >                 Though avoiding a n^2 behaviour here is probably a good
> >> > idea anyway.    
> >> 
> >> Agreed.  
> 
> Patch posted:
> 
>     Subject: [PATCH for-5.1 5/5] qom: Make info qom-tree sort children more efficiently
>     Message-Id: <20200714160202.3121879-6-armbru@redhat.com>
> 


-- 
David Gibson <dgibson@redhat.com>
Principal Software Engineer, Virtualization, Red Hat

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  reply	other threads:[~2020-07-17  6:01 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27  8:47 [PATCH 0/2] qom: Make "info qom-tree" show children sorted Markus Armbruster
2020-05-27  8:47 ` [PATCH 1/2] qom: Constify object_get_canonical_path{, _component}()'s parameter Markus Armbruster
2020-05-27  9:02   ` Cédric Le Goater
2020-05-27  9:49   ` [PATCH 1/2] qom: Constify object_get_canonical_path{,_component}()'s parameter Philippe Mathieu-Daudé
2020-05-27  8:47 ` [PATCH 2/2] qom: Make "info qom-tree" show children sorted Markus Armbruster
2020-05-27  9:04   ` Cédric Le Goater
2020-05-27 10:31   ` Philippe Mathieu-Daudé
2020-07-07  4:45   ` Slow down with: 'Make "info qom-tree" show children sorted' Thomas Huth
2020-07-07  4:58     ` Philippe Mathieu-Daudé
2020-07-07  5:33       ` Markus Armbruster
2020-07-07  8:00         ` Paolo Bonzini
2020-07-07 12:00           ` Markus Armbruster
2020-07-07 12:04             ` Daniel P. Berrangé
2020-07-13  1:13             ` David Gibson
2020-07-13 16:13               ` Markus Armbruster
2020-07-15 23:59                 ` David Gibson
2020-07-16  5:37                   ` Markus Armbruster
2020-07-17  6:00                     ` David Gibson [this message]
2020-07-07  8:46     ` Daniel P. Berrangé
2020-07-07  9:06       ` Paolo Bonzini
2020-07-07  9:40     ` Daniel P. Berrangé
2020-07-07  9:49       ` Paolo Bonzini
2020-07-08  9:24       ` Markus Armbruster
2020-06-08 12:09 ` [PATCH 0/2] qom: Make "info qom-tree" show children sorted Mark Cave-Ayland

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