From: linas@austin•ibm.com (Linas Vepstas)
To: Nathan Lynch <ntl@pobox•com>
Cc: linuxppc-dev@ozlabs•org, anton@au1•ibm.com,
Srinivasa Ds <srinivasa@in•ibm.com>,
paulus@samba•org, ego@in•ibm.com
Subject: Re: [RFC] [PATCH] cpu hotplug on power based systems.
Date: Thu, 16 Nov 2006 15:02:03 -0600 [thread overview]
Message-ID: <20061116210203.GC23600@austin.ibm.com> (raw)
In-Reply-To: <20061116154051.GB2008@localdomain>
On Thu, Nov 16, 2006 at 09:40:51AM -0600, Nathan Lynch wrote:
> Srinivasa Ds wrote:
> >
> > Linux kernel uses some of the rtas token to perform cpu hotplug on power
> > systems. Some of the systems may not provide all the rtas services,which
> > are required to perform cpu hotplug. Like for example
> > 1) JS20 doesn't provide "stop-self" token and cpu hotplug operations
> > on these systems causes system to crash.
> > 2) some of the p630 systems doesn't provide "query-cpu-stopped-state"
> > token and we are not sure of whether cpu is under stopped state or not
> > or stop-self is still in progress .
>
> Neither of these systems (well, the p630 in "SMP" mode) have
> hypervisors so their firmwares don't provide the rtas primitives for
> CPU offline.
>
> > So we can't take decision on whether cpu really has gone offline or not.
> >
> > So we need to make sure that all required rtas tokens for cpu hotplug
> > are available during rtas initialization phase and to disable cpu
> > hotplug if they are not available.
> > I have developed the patch which does the above thing. Please let me
> > know your comments on this.
>
> Would be better to either a) inhibit creation of the sysfs 'online'
> cpu attributes (I thought we used to handle this correctly on these
> systems) or b) use the generic cpu hotplug operations which have no
> dependency on RTAS.
Yeah, good point. It seemes cleaner to do this, than to add a new
state ("per disabled") that adds complexity to the generic kernel code.
Perhaps we could set this up so that, if rtas "stop-self" is not
defined, then generic_cpu_die() is installed instead of pseries_cpu_die()?
--linas
next prev parent reply other threads:[~2006-11-16 21:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-16 14:39 [RFC] [PATCH] cpu hotplug on power based systems Srinivasa Ds
2006-11-16 15:40 ` Nathan Lynch
2006-11-16 21:02 ` Linas Vepstas [this message]
2006-11-17 3:36 ` [PATCH] Reorganise and then fixup the pseries cpu hotplug code Michael Ellerman
2006-11-17 3:59 ` Michael Ellerman
2006-11-17 4:31 ` Stephen Rothwell
2006-11-17 4:44 ` Michael Ellerman
2006-11-17 5:02 ` Stephen Rothwell
2006-11-17 18:11 ` Linas Vepstas
2006-11-20 0:44 ` Michael Ellerman
2006-11-17 18:04 ` Linas Vepstas
2006-11-20 1:08 ` Michael Ellerman
2006-11-20 4:22 ` jschopp
2006-11-20 5:59 ` Michael Ellerman
2006-11-21 16:43 ` Nathan Lynch
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