Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752958AbbDUMvP (ORCPT ); Tue, 21 Apr 2015 08:51:15 -0400 Received: from foss.arm.com ([217.140.101.70]:46744 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750960AbbDUMvM (ORCPT ); Tue, 21 Apr 2015 08:51:12 -0400 Message-ID: <553647BB.6030408@arm.com> Date: Tue, 21 Apr 2015 13:51:07 +0100 From: Marc Zyngier Organization: ARM Ltd User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0 MIME-Version: 1.0 To: Daniel Thompson , Thomas Gleixner , Jason Cooper CC: Russell King , Will Deacon , Catalin Marinas , Stephen Boyd , John Stultz , Steven Rostedt , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "patches@linaro.org" , "linaro-kernel@lists.linaro.org" , Sumit Semwal , Dirk Behme , Daniel Drake , Dmitry Pervushin , Tim Sander Subject: Re: [RESEND PATCH 4.0-rc7 v20 1/6] irqchip: gic: Optimize locking in gic_raise_softirq References: <1427216014-5324-1-git-send-email-daniel.thompson@linaro.org> <1428659511-9590-1-git-send-email-daniel.thompson@linaro.org> <1428659511-9590-2-git-send-email-daniel.thompson@linaro.org> In-Reply-To: <1428659511-9590-2-git-send-email-daniel.thompson@linaro.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1409 Lines: 38 On 10/04/15 10:51, Daniel Thompson wrote: > Currently gic_raise_softirq() is locked using upon irq_controller_lock. > This lock is primarily used to make register read-modify-write sequences > atomic but gic_raise_softirq() uses it instead to ensure that the > big.LITTLE migration logic can figure out when it is safe to migrate > interrupts between physical cores. > > This is sub-optimal in closely related ways: > > 1. No locking at all is required on systems where the b.L switcher is > not configured. > > 2. Finer grain locking can be used on systems where the b.L switcher is > present. > > This patch resolves both of the above by introducing a separate finer > grain lock and providing conditionally compiled inlines to lock/unlock > it. > > Signed-off-by: Daniel Thompson > Cc: Thomas Gleixner > Cc: Jason Cooper > Cc: Russell King > Cc: Marc Zyngier > Acked-by: Nicolas Pitre Looks good to me. Acked-by: Marc Zyngier M. -- Jazz is not dead. It just smells funny... -- 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/