Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752256Ab3HABgS (ORCPT ); Wed, 31 Jul 2013 21:36:18 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:52197 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751485Ab3HABgQ (ORCPT ); Wed, 31 Jul 2013 21:36:16 -0400 Message-ID: <51F9BB8D.6060907@codeaurora.org> Date: Wed, 31 Jul 2013 18:36:13 -0700 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: Timur Tabi , Andrew Morton CC: Arpit Goel , linux@arm.linux.org.uk, takata@linux-m32r.org, philb@gnu.org, Geert Uytterhoeven , schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, linux390@de.ibm.com, David Miller , Rob Herring , Arnd Bergmann , Stephen Warren , john.stultz@linaro.org, jesper.nilsson@axis.com, gregkh@linuxfoundation.org, sam@ravnborg.org, "linux-arm-kernel@lists.infradead.org" , lkml , linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org, linux-m68k@vger.kernel.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, mattw@codeaurora.org Subject: Re: [PATCH 2/2] Convert PowerPC macro spin_event_timeout() to architecture independent macro References: <1375187900-17582-1-git-send-email-B44344@freescale.com> <1375187900-17582-3-git-send-email-B44344@freescale.com> <20130731071630.GI8868@codeaurora.org> <51F9A5FE.8030608@codeaurora.org> <51F9A80E.5010307@tabi.org> <51F9A8F1.9020704@codeaurora.org> <51F9A9CD.1040804@tabi.org> In-Reply-To: <51F9A9CD.1040804@tabi.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1749 Lines: 41 On 07/31/13 17:20, Timur Tabi wrote: > On 07/31/2013 07:16 PM, Stephen Boyd wrote: >> cpu_relax() is usually just a compiler barrier or an instruction hint to >> the cpu that it should cool down because we're spinning in a tight loop. >> It certainly shouldn't be calling into the scheduler. > Ah yes, I remember now. So it does seem that if we can fix the problem > of non-incrementing 'jiffies', then this macro can be used in interrupts. That's encouraging. It looks like you introduced it to use in interrupt context but then it got shot down[1]? I lost track in all the versions. > > Of course, that assumes that spinning in interrupt context is a good > idea to begin with. Maybe we shouldn't be encouraging it? I read through the v5 discussion and it seems I'm about to walk through some tall grass on the way to Cerulean City. Andrew Morton, I choose you! Use your mind-power move to convince everyone that having a macro for spinning on a register in interrupt context is a good thing. At least it will be more obvious. > >>>> FYI, you might want to look at the code reviews for spin_event_timeout() >>>> on the linuxppc-dev mailing list, back in March 2009. >>>> >> Sure. Any pointers? Otherwise I'll go digging around the archives. > https://lists.ozlabs.org/pipermail/linuxppc-dev/2009-March/thread.html > [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2009-May/072521.html -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/