[Sidefx-houdini-list] stability of mantra on multi core machines?

Frederic Servant frederic.servant at gmail.com
Tue Jul 29 20:15:50 EDT 2008


Hi Antoine,

Yes, you save memory overall, and possibly some i/o wait. If your data stays
in the cache often it can also be faster than linear.

But, if you have enough memory, you can launch several processes at the
same time, even multithreaded ones. I do that sometimes to speed up the
renderings.

As long as you are not swapping, and if your job does not scale well over
eight cores (my detector is a load average significantly below 8, for 8
cores),
you render faster overall, even if the individual frame render times are
higher.

My explanation is that less CPU cycles are wasted if your load average is
above 8. I managed to gain up to 35% on certain passes.

I hope this makes sense.

Cheers,
--
Frederic Servant
la maison
www.alamaison.fr



  we sometimes launch  mnulti-threaded

On Wed, Jul 30, 2008 at 12:47 AM, Antoine Durr <antoine at floqfx.com> wrote:

> A question for all of you rendering on multi-cores: are you in effect
> starting to treat your renderfarm as individual hosts rather than as
> multiple hosts?  I.e. I'm unclear as to the benefit of rendering 1
> frame on n cores vs. running n frames on n cores.  Is it that the
> memory footprint is getting so big that you're consolidating cores to
> bulk up on ram for the given job?  Just curious.  Thanks!
>
> -- Antoine
>
> On Jul 29, 2008, at 3:27 PM, Frederic Servant wrote:
>
> > Hi,
> >
> > We recently used mantra for rendering fur and we ended up writting
> > a script
> > to:
> >  - retry after a crash
> >  - verify the integrity of each frame and retry
> >  - kill the render process after a timeout and retry
> > The render times were good except for those missed frames. We are
> > running
> > 9.1.244 on eight cores.
> >
> > I hope this is improved in 9.5, I will try.
> >
> > Cheers,
> > --
> > Frederic Servant
> > la maison
> > www.alamaison.fr
> >
> >
> > On Tue, Jul 29, 2008 at 6:17 PM, Michael K O'Brien
> > <mobrien at pixar.com>wrote:
> >
> >> Hola~
> >>
> >> Yes. If the render cores out, it's pretty easy to detect that and
> >> retry the
> >> frame. However, it constantly just deadlocks. I can't imagine
> >> trying to use
> >> mantra on a production.
> >>
> >> MO
> >>
> >> --
> >> Michael K O'Brien
> >> mobrien at pixar.com
> >> Pixar
> >>
> >> JEN: Just because it's Taco Bell doesn't mean it's not dinner!
> >>
> >>> -----Original Message-----
> >>> From: sidefx-houdini-list-bounces at sidefx.com [mailto:
> >> sidefx-houdini-list-
> >>> bounces at sidefx.com] On Behalf Of Simon Kapeniak
> >>> Sent: Tuesday, July 29, 2008 12:49 AM
> >>> To: sidefx-houdini-list at sidefx.com
> >>> Subject: Re: [Sidefx-houdini-list] stability of mantra on multi core
> >>> machines?
> >>>
> >>> The question is why 8 cores rendering eats much more memory then
> >>> 1 core.
> >>> Don't cores share memory? I understand 20% differences, but
> >>> Mantra likes
> >>> to
> >>> take as big as  twice ram in mulithreding mode. It also doesn't
> >>> explain
> >>> the
> >>> situation in which mantra doesn't fail but freezes on a few
> >>> buckets in
> >>> multi-core rendering.
> >>>
> >>> 2008/7/29 Pablo Giménez <pablogipi at gmail.com>
> >>>
> >>>> Yes unfortunately, when you reach the memory limit of your
> >>>> machines you
> >>> get
> >>>> random fails, and mantr exists only with a segfault, very bad.
> >>>> I has a similar problems some months ago and I rememberd struggling
> >>> myself
> >>>> trying to find the problem and it was the memory, nothing else, but
> >>> because
> >>>> Mantra exists without any info you can waste a lot of time
> >>>> trying to
> >>> figure
> >>>> out what is happening.
> >>>> And also, rendering with 4 cores seems pretty solid, with eith
> >>>> cores I
> >>> have
> >>>> experimented problems in early versions if mantra 9 and 9.1.
> >>>> Cheers
> >>>>
> >>>> 2008/7/28 paul simpson <paul at realisestudio.com>
> >>>>
> >>>>> for linux: man ulimit
> >>>>>
> >>>>> 2008/7/28 Guillaume Laforge <guillaume at alamaison.fr>
> >>>>>
> >>>>>> We've got the memory limit problem here when rendering fur
> >>> procedurals
> >>>> !
> >>>>>> If the memory is closed to the limit, frames randomly crash.
> >>>>>> As a workaround we set a time bomb on our rendermanager to
> >> re-render
> >>>>>> those bad frames. The same frames can crash twice or more and
> >>>>>> then
> >>>>>> render fine.
> >>>>>> I don't know if there is a way to set a memory limit in Mantra as
> >> in
> >>>>>> Mental Ray ?
> >>>>>>
> >>>>>> Cheers
> >>>>>>
> >>>>>> Guillaume Laforge | la maison <http://www.alamaison.fr>
> >>>>>> my new little blog : http://frenchdog.wordpress.com/
> >>>>>> <http://frenchdog.wordpress.com/>
> >>>>>>
> >>>>>>
> >>>>>> Guillaume Laforge a écrit :
> >>>>>>> _______________________________________________
> >>>>>>> Sidefx-houdini-list mailing list
> >>>>>>> Sidefx-houdini-list at sidefx.com
> >>>>>>>
> >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>>>>>>
> >>>>>> _______________________________________________
> >>>>>> Sidefx-houdini-list mailing list
> >>>>>> Sidefx-houdini-list at sidefx.com
> >>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>>>>>
> >>>>> _______________________________________________
> >>>>> Sidefx-houdini-list mailing list
> >>>>> Sidefx-houdini-list at sidefx.com
> >>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>>>>
> >>>>
> >>>>
> >>>>
> >>>> --
> >>>> Un saludo
> >>>> Best Regards
> >>>> Pablo Giménez
> >>>> _______________________________________________
> >>>> Sidefx-houdini-list mailing list
> >>>> Sidefx-houdini-list at sidefx.com
> >>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>>>
> >>> _______________________________________________
> >>> Sidefx-houdini-list mailing list
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> >>
> >> _______________________________________________
> >> Sidefx-houdini-list mailing list
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> >>
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> > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>
> -- Antoine
>
> Floq FX Inc.
> 10659 Cranks Rd.
> Culver City, CA 90230
> 310/430-2473
>
>
>
>
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