From: Peter Zijlstra <peterz@infradead.org>
To: Jesse Larrew <jlarrew@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [BUG] rebuild_sched_domains considered dangerous
Date: Fri, 03 Jun 2011 16:47:49 +0200 [thread overview]
Message-ID: <1307112469.2353.3402.camel@twins> (raw)
In-Reply-To: <4DCAB6B0.8020904@linux.vnet.ibm.com>
On Wed, 2011-05-11 at 11:17 -0500, Jesse Larrew wrote:
> > I would really like to see both patch-sets together. Also, I'm not
> at
> > all convinced its a sane thing to do. Pretty much all NUMA aware
> > software I know of assumes that CPU<->NODE relations are static,
> > breaking that in kernel renders all existing software broken.
> >=20
>=20
> I suspect that's true. Then again, shouldn't it be the capabilities of
> the hardware that dictates what the software does, rather than the
> other way around?=20
Wish that were true, we wouldn't be all constrained by all this legacy
software.. ;-)
Anyway, there's plenty of CPU<->NODE assumptions in the kernel as well,
fixing those will be 'interesting' at best, as for userspace, since its
a user-driven tool revamping the topology the user gets to keep the
pieces when he runs that while some NUMA aware proglet is running.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Jesse Larrew <jlarrew@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
nfont@austin.ibm.com
Subject: Re: [BUG] rebuild_sched_domains considered dangerous
Date: Fri, 03 Jun 2011 16:47:49 +0200 [thread overview]
Message-ID: <1307112469.2353.3402.camel@twins> (raw)
In-Reply-To: <4DCAB6B0.8020904@linux.vnet.ibm.com>
On Wed, 2011-05-11 at 11:17 -0500, Jesse Larrew wrote:
> > I would really like to see both patch-sets together. Also, I'm not
> at
> > all convinced its a sane thing to do. Pretty much all NUMA aware
> > software I know of assumes that CPU<->NODE relations are static,
> > breaking that in kernel renders all existing software broken.
> >
>
> I suspect that's true. Then again, shouldn't it be the capabilities of
> the hardware that dictates what the software does, rather than the
> other way around?
Wish that were true, we wouldn't be all constrained by all this legacy
software.. ;-)
Anyway, there's plenty of CPU<->NODE assumptions in the kernel as well,
fixing those will be 'interesting' at best, as for userspace, since its
a user-driven tool revamping the topology the user gets to keep the
pieces when he runs that while some NUMA aware proglet is running.
next prev parent reply other threads:[~2011-06-03 14:48 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-09 2:58 [BUG] rebuild_sched_domains considered dangerous Benjamin Herrenschmidt
2011-03-09 2:58 ` Benjamin Herrenschmidt
2011-03-09 10:19 ` Peter Zijlstra
2011-03-09 10:19 ` Peter Zijlstra
2011-03-09 11:33 ` Peter Zijlstra
2011-03-09 11:33 ` Peter Zijlstra
2011-03-09 13:15 ` Martin Schwidefsky
2011-03-09 13:15 ` Martin Schwidefsky
2011-03-09 13:19 ` Peter Zijlstra
2011-03-09 13:19 ` Peter Zijlstra
2011-03-09 13:31 ` Martin Schwidefsky
2011-03-09 13:31 ` Martin Schwidefsky
2011-03-09 13:33 ` Peter Zijlstra
2011-03-09 13:33 ` Peter Zijlstra
2011-03-09 13:46 ` Martin Schwidefsky
2011-03-09 13:46 ` Martin Schwidefsky
2011-03-09 13:54 ` Peter Zijlstra
2011-03-09 13:54 ` Peter Zijlstra
2011-03-09 15:26 ` Steven Rostedt
2011-03-09 15:26 ` Steven Rostedt
2011-03-09 13:01 ` Peter Zijlstra
2011-03-09 13:01 ` Peter Zijlstra
2011-03-10 14:10 ` Peter Zijlstra
2011-03-10 14:10 ` Peter Zijlstra
2011-04-20 10:07 ` Peter Zijlstra
2011-04-20 10:07 ` Peter Zijlstra
2011-04-20 22:01 ` Benjamin Herrenschmidt
2011-04-20 22:01 ` Benjamin Herrenschmidt
2011-05-09 21:26 ` Jesse Larrew
2011-05-10 14:09 ` Peter Zijlstra
2011-05-10 14:09 ` Peter Zijlstra
2011-05-11 16:17 ` Jesse Larrew
2011-05-11 16:17 ` Jesse Larrew
2011-06-03 14:47 ` Peter Zijlstra [this message]
2011-06-03 14:47 ` Peter Zijlstra
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