Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754875AbbKMP1a (ORCPT ); Fri, 13 Nov 2015 10:27:30 -0500 Received: from www.linutronix.de ([62.245.132.108]:60406 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754225AbbKMP13 (ORCPT ); Fri, 13 Nov 2015 10:27:29 -0500 Date: Fri, 13 Nov 2015 10:26:42 -0500 (EST) From: Thomas Gleixner To: Marc Gonzalez cc: Daniel Lezcano , LKML , Linux ARM , Arnd Bergmann Subject: Re: [PATCH] clocksource/drivers/tango-xtal: Replace code by clocksource_mmio_init In-Reply-To: <5645F616.9060707@sigmadesigns.com> Message-ID: References: <1447412292-841-1-git-send-email-daniel.lezcano@linaro.org> <5645D5A0.1000502@sigmadesigns.com> <5645F0D0.4060503@linaro.org> <5645F616.9060707@sigmadesigns.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1147 Lines: 40 On Fri, 13 Nov 2015, Marc Gonzalez wrote: > On 13/11/2015 15:16, Daniel Lezcano wrote: > > For example: > > > > struct clockcommon { > > u32 mult; > > u32 shift; > > int rating; > > void __iomem *base; > > char *name; > > int irq; > > }; > > > > struct clocksource { > > struct clockcommon common; /* MUST be the first field */ > > cycle_t (*read)(struct clocksource *cs); > > cycle_t mask; > > ... > > }; > > According to my notes, commit 369db4c952 grouped hot-path data > into a single cache line (hence ____cacheline_aligned). > > (AFAIR, ARMv7 ARCH_MULTIPLATFORM assumes CACHE_LINE=64) > > Not sure how to make the two concepts (common base struct and > grouping hot data) play nicely, without wasting a lot of space > on padding. It wont play well. We are not going to change the layout of struct clocksource because it will hurt the sane use cases for no reason. Thanks, tglx -- 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/