From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH 0/2] Kill unused parameter to smp_call_function and friends Date: Sat, 31 May 2008 22:45:42 +0200 Message-ID: <20080531204541.GK5405@ucw.cz> References: <1212051661-12733-1-git-send-email-jens.axboe@oracle.com> <20080529114132.663eff4b@core> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from gprs189-60.eurotel.cz ([160.218.189.60]:4289 "EHLO spitz.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752721AbYFAOpL (ORCPT ); Sun, 1 Jun 2008 10:45:11 -0400 Content-Disposition: inline In-Reply-To: <20080529114132.663eff4b@core> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Alan Cox Cc: Jens Axboe , linux-kernel@vger.kernel.org, peterz@infradead.org, npiggin@suse.de, linux-arch@vger.kernel.org, jeremy@goop.org, mingo@elte.hu, paulmck@linux.vnet.ibm.com Hi! > > It bothers me how the smp call functions accept a 'nonatomic' or 'retry' > > parameter (depending on who you ask), but don't do anything with it. > > So kill that silly thing. > > > > Two patches here, one for smp_call_function*() and one for on_each_cpu(). > > This patchset applies on top of the generic-ipi patchset just sent out. > > Which leads to notice that we seem to have acquired a bug somewhere on > the way. smp_call_function on x86 is it seems to me implemented as > "smp_call_function and occasionally run it multiple times" > > One of the joys of the older x86 APIC setups is the APIC messaging bus. > This can get checksum errors in which case the message is retransmitted: > > In the specific case a message is retransmitted and there are at least > three parties on the bus (2 CPU APICs and an IOAPIC is enough) you can > get a situation where one receiver gets the message the second receiver > errors it and the retransmit causes the IPI to be repeated which causes > the IPI to be redelivered. Does that mean smp_call_function on i386 should have a bitmap of cpus the message was already delivered to, and drop the duplicates? -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html