From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753118AbbCWNTW (ORCPT ); Mon, 23 Mar 2015 09:19:22 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:40197 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752340AbbCWNTU (ORCPT ); Mon, 23 Mar 2015 09:19:20 -0400 Date: Mon, 23 Mar 2015 14:19:05 +0100 From: Peter Zijlstra To: Vincent Guittot Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, preeti@linux.vnet.ibm.com, Morten.Rasmussen@arm.com, kamalesh@linux.vnet.ibm.com, riel@redhat.com, efault@gmx.de, nicolas.pitre@linaro.org, dietmar.eggemann@arm.com, linaro-kernel@lists.linaro.org, Paul Turner , Ben Segall Subject: Re: [PATCH v10 04/11] sched: Make sched entity usage tracking scale-invariant Message-ID: <20150323131905.GF23123@twins.programming.kicks-ass.net> References: <1425052454-25797-1-git-send-email-vincent.guittot@linaro.org> <1425052454-25797-5-git-send-email-vincent.guittot@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1425052454-25797-5-git-send-email-vincent.guittot@linaro.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 27, 2015 at 04:54:07PM +0100, Vincent Guittot wrote: > + unsigned long scale_freq = arch_scale_freq_capacity(NULL, cpu); > + sa->running_avg_sum += delta_w * scale_freq > + >> SCHED_CAPACITY_SHIFT; so the only thing that could be improved is somehow making this multiplication go away when the arch doesn't implement the function. But I'm not sure how to do that without #ifdef. Maybe a little something like so then... that should make the compiler get rid of those multiplications unless the arch needs them. --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2484,8 +2484,6 @@ static u32 __compute_runnable_contrib(u6 return contrib + runnable_avg_yN_sum[n]; } -unsigned long __weak arch_scale_freq_capacity(struct sched_domain *sd, int cpu); - /* * We can represent the historical contribution to runnable average as the * coefficients of a geometric series. To do this we sub-divide our runnable @@ -6015,11 +6013,6 @@ static unsigned long default_scale_capac return SCHED_CAPACITY_SCALE; } -unsigned long __weak arch_scale_freq_capacity(struct sched_domain *sd, int cpu) -{ - return default_scale_capacity(sd, cpu); -} - static unsigned long default_scale_cpu_capacity(struct sched_domain *sd, int cpu) { if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1)) --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1387,7 +1387,14 @@ static inline int hrtick_enabled(struct #ifdef CONFIG_SMP extern void sched_avg_update(struct rq *rq); -extern unsigned long arch_scale_freq_capacity(struct sched_domain *sd, int cpu); + +#ifndef arch_scale_freq_capacity +static __always_inline +unsigned long arch_scale_freq_capacity(struct sched_domain *sd, int cpu) +{ + return SCHED_CAPACITY_SCALE; +} +#endif static inline void sched_rt_avg_update(struct rq *rq, u64 rt_delta) {