From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Peter Zijlstra In-Reply-To: <1297232054.14982.346.camel@pasglop> References: <1295262433.30950.53.camel@laptop> <1297034792.14982.10.camel@pasglop> <1297086859.13327.16.camel@laptop> <1297232054.14982.346.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 09 Feb 2011 10:37:24 +0100 Message-ID: <1297244244.13327.147.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org Subject: Re: [PATCH] sched: provide scheduler_ipi() callback in response to smp_send_reschedule() To: Benjamin Herrenschmidt Cc: Richard Henderson , Ivan Kokshaysky , Matt Turner , Russell King , Mike Frysinger , Mikael Starvik , Jesper Nilsson , Tony Luck , Fenghua Yu , Hirokazu Takata , Ralf Baechle , David Howells , Koichi Yasutake , Kyle McMartin , Helge Deller , "James E.J. Bottomley" , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, Paul Mundt , "David S. Miller" , Chris Metcalf , Jeff Dike , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Jeremy Fitzhardinge , Konrad Rzeszutek Wilk , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, uclinux-dist-devel@blackfin.uclinux.org, linux-cris-kernel@axis.com, linux-ia64@vger.kernel.org, linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org, linux-mips@linux-mips.org, linux-am33-list@redhat.com, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, user-mode-linux-user@lists.sourceforge.net, xen-devel@lists.xensource.com, virtualization@lists.osdl.org, Linux-Arch List-ID: On Wed, 2011-02-09 at 17:14 +1100, Benjamin Herrenschmidt wrote: > On Mon, 2011-02-07 at 14:54 +0100, Peter Zijlstra wrote: > > On Mon, 2011-02-07 at 10:26 +1100, Benjamin Herrenschmidt wrote: > > > You missed: > > > > > > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c > > > index 9813605..467d122 100644 > > > --- a/arch/powerpc/kernel/smp.c > > > +++ b/arch/powerpc/kernel/smp.c > > > @@ -98,6 +98,7 @@ void smp_message_recv(int msg) > > > break; > > > case PPC_MSG_RESCHEDULE: > > > /* we notice need_resched on exit */ > > > + scheduler_ipi(); > > > break; > > > case PPC_MSG_CALL_FUNC_SINGLE: > > > generic_smp_call_function_single_interrupt(); > > > > > > Fold that in and add: > > > > > > Acked-by: Benjamin Herrenschmidt > > > > Thanks Ben! > > BTW. I we lurking at some of our CPU hotplug code and I think I cannot > totally guarantee that this won't be called on an offline CPU. If that's > a problem, you may want to add a test for that. > > IE. The call function IPIs are normally not going to be sent to an > offlined CPU, and stop_machine should be a good enough fence here, but > we do abuse reschedule for a number of things (including in some case > to wake up a sleeping CPU that was pseudo-offlined :-) Hmm, I _think_ that should all work out nicely, but we'll see, if when this stuff hits the tree powerpc machines start falling over we'd better put that check in ;-) Meanwhile I'm going to preserve this comment in the changelog of this patch so we don't forget.