From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e2.ny.us.ibm.com (e2.ny.us.ibm.com [32.97.182.142]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e2.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id B09EC67BD3 for ; Fri, 17 Nov 2006 08:02:09 +1100 (EST) Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e2.ny.us.ibm.com (8.13.8/8.12.11) with ESMTP id kAGL24X3001740 for ; Thu, 16 Nov 2006 16:02:04 -0500 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay02.pok.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id kAGL24GE224440 for ; Thu, 16 Nov 2006 16:02:04 -0500 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id kAGL23XI020623 for ; Thu, 16 Nov 2006 16:02:04 -0500 Date: Thu, 16 Nov 2006 15:02:03 -0600 To: Nathan Lynch Subject: Re: [RFC] [PATCH] cpu hotplug on power based systems. Message-ID: <20061116210203.GC23600@austin.ibm.com> References: <455C783E.2040701@in.ibm.com> <20061116154051.GB2008@localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20061116154051.GB2008@localdomain> From: linas@austin.ibm.com (Linas Vepstas) Cc: linuxppc-dev@ozlabs.org, anton@au1.ibm.com, Srinivasa Ds , paulus@samba.org, ego@in.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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