From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 11/11] s390: convert to generic helpers for IPI function calls Date: Wed, 23 Apr 2008 10:11:48 +0200 Message-ID: <20080423081147.GC12774@kernel.dk> References: <1208890227-24808-1-git-send-email-jens.axboe@oracle.com> <1208890227-24808-12-git-send-email-jens.axboe@oracle.com> <20080423075831.GB15850@osiris.boeblingen.de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20080423075831.GB15850-Pmgahw53EmNLmI7Nx2oIsGnsbthNF6/HVpNB7YpNyf8@public.gmane.org> Sender: linux-arch-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: To: Heiko Carstens Cc: linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, npiggin-l3A5Bk7waGM@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, sam-uyr5N9Q2VtJg9hUCZPvPmw@public.gmane.org, Martin Schwidefsky On Wed, Apr 23 2008, Heiko Carstens wrote: > On Tue, Apr 22, 2008 at 08:50:27PM +0200, Jens Axboe wrote: > > This converts s390 to use the new helpers for smp_call_function() and > > friends, and adds support for smp_call_function_single(). Not tested, > > but it compiles. > > > > Cc: Martin Schwidefsky > > Cc: Heiko Carstens > > Signed-off-by: Jens Axboe > > Your generic patch changes semantics of smp_call_function(). At least the > s390 version of smp_call_function() mask used to not return unless all IPIs > where received on the target cpus. > Your patch changes that. It will already return as soon as all IPIs have > been sent. Unfortunately Martin's etr code in arch/s390/kernel/time.c Yep, this is what I mentioned in the intro mail. > relies on exactly the old semantics. OK, I could not see anything which relied on that and I did think that it was a somewhat odd interface. By the time that smp_call_function() stops waiting for startups, we could easily be in the condition that the N-1 CPUs executed the function part a long time ago. I just didn't see much usefulness in that, you may as well just set wait == 1 in that case. > Since this seems to be an s390 only issue, could you just drop the s390 > conversion patch? We'll have to think about how to change the err code > and convert later I guess. I'll drop the s390 bits. I can easily add something like smp_call_function_foo() that has this behaviour. -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from brick.kernel.dk ([87.55.233.238]:25406 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751965AbYDWILw (ORCPT ); Wed, 23 Apr 2008 04:11:52 -0400 Date: Wed, 23 Apr 2008 10:11:48 +0200 From: Jens Axboe Subject: Re: [PATCH 11/11] s390: convert to generic helpers for IPI function calls Message-ID: <20080423081147.GC12774@kernel.dk> References: <1208890227-24808-1-git-send-email-jens.axboe@oracle.com> <1208890227-24808-12-git-send-email-jens.axboe@oracle.com> <20080423075831.GB15850@osiris.boeblingen.de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080423075831.GB15850@osiris.boeblingen.de.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Heiko Carstens Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, npiggin@suse.de, torvalds@linux-foundation.org, peterz@infradead.org, sam@ravnborg.org, Martin Schwidefsky Message-ID: <20080423081148.vy261-z-X8wzb048ldVDjwl4VvWw1UDtsQrqnsa9Dkg@z> On Wed, Apr 23 2008, Heiko Carstens wrote: > On Tue, Apr 22, 2008 at 08:50:27PM +0200, Jens Axboe wrote: > > This converts s390 to use the new helpers for smp_call_function() and > > friends, and adds support for smp_call_function_single(). Not tested, > > but it compiles. > > > > Cc: Martin Schwidefsky > > Cc: Heiko Carstens > > Signed-off-by: Jens Axboe > > Your generic patch changes semantics of smp_call_function(). At least the > s390 version of smp_call_function() mask used to not return unless all IPIs > where received on the target cpus. > Your patch changes that. It will already return as soon as all IPIs have > been sent. Unfortunately Martin's etr code in arch/s390/kernel/time.c Yep, this is what I mentioned in the intro mail. > relies on exactly the old semantics. OK, I could not see anything which relied on that and I did think that it was a somewhat odd interface. By the time that smp_call_function() stops waiting for startups, we could easily be in the condition that the N-1 CPUs executed the function part a long time ago. I just didn't see much usefulness in that, you may as well just set wait == 1 in that case. > Since this seems to be an s390 only issue, could you just drop the s390 > conversion patch? We'll have to think about how to change the err code > and convert later I guess. I'll drop the s390 bits. I can easily add something like smp_call_function_foo() that has this behaviour. -- Jens Axboe