From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7565FC2BA83 for ; Thu, 13 Feb 2020 12:26:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3E36E217F4 for ; Thu, 13 Feb 2020 12:26:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=verdurent-com.20150623.gappssmtp.com header.i=@verdurent-com.20150623.gappssmtp.com header.b="za3rTGuO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729912AbgBMM0A (ORCPT ); Thu, 13 Feb 2020 07:26:00 -0500 Received: from mail-vk1-f193.google.com ([209.85.221.193]:39328 "EHLO mail-vk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729428AbgBMM0A (ORCPT ); Thu, 13 Feb 2020 07:26:00 -0500 Received: by mail-vk1-f193.google.com with SMTP id t129so1509718vkg.6 for ; Thu, 13 Feb 2020 04:25:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=verdurent-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Y9OAQr7LoJ7FysjO3RNUdQHAVxo4VqZp7WZsTWIAp+U=; b=za3rTGuOnSDnmFdxj8VAeh6VbheBiDSorET9lsV9J155E17dBflM5Xa9yAtAtLXMEi 9sqlhC2kF38nbcDs/pGUEtArCN2mKNq0gAKiD7Rfb51LiekGYAIq1V+7izfDNnXhCK/f cVxutZZ2DCdaJAJTtmtv8/sB9cMCsNRQxOhvq/gkQRCN3MRcat5b6l4Xjo3kCIYfLDZM gJSDN6HyELXmqWSciasKZ9Joi3OKM9OsfrioBPAGfLuj6a4xFniu8RelliOtSsSPj6HV NYksR+LMCkDHzxsKVjrC00nC3T+Fingk5iyd9+BE3JjF11VWM7gzZUG3nlqaNnb353DA k45Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Y9OAQr7LoJ7FysjO3RNUdQHAVxo4VqZp7WZsTWIAp+U=; b=UllCEj8PKfY1Ehr5g8AdLukdRCDz8CMAFWvjk3p4f0B+WU5verst6oVeyLibYhIsZr q2KGKECl4dDIpbXjXVVcug3YEpGdKpO6+NWMxJFghDdGvBcNcjzq1S3oDdT94fzXr5tF kP+pOXm5BEdCZ2xqD5SGZ+rjQgPJbtkAfFGZhwjEuKui42B35FlZI266v13K4/8Rj3gq woAW6nP0it7h6oEhaInens9i7Wjmx2n5wcgEzooe4y/BmHBPD/aqXAevSiY4Egp2uegZ /98JwMilSZ2aAWMjXQFJ0iCUv+WbrllgEEZs3+OOXJ7yUHCI6sAAxUVyf3SrIWTa4pkx +ieg== X-Gm-Message-State: APjAAAUcx+FU+aWFy7qnkKlsv4kMN8Y9oHcqiSFY8c+7gPOPAhzpxMOG N0YFjlLeSst6X19lnpBcNiqp8qLCEWQTOoIXWpOtqA== X-Google-Smtp-Source: APXvYqxsuxYSXPiHZ4iLR27psVWCXL6kFFq0BEbhNoMUh8EG5yW9x4+cRmT9OrPpHEInL8yQKRZeXBglBQMFpDg607o= X-Received: by 2002:ac5:c7a9:: with SMTP id d9mr1812766vkn.79.1581596758533; Thu, 13 Feb 2020 04:25:58 -0800 (PST) MIME-Version: 1.0 References: <1580250967-4386-1-git-send-email-thara.gopinath@linaro.org> <1580250967-4386-4-git-send-email-thara.gopinath@linaro.org> In-Reply-To: <1580250967-4386-4-git-send-email-thara.gopinath@linaro.org> From: Amit Kucheria Date: Thu, 13 Feb 2020 17:55:47 +0530 Message-ID: Subject: Re: [Patch v9 3/8] arm,arm64,drivers:Add infrastructure to store and update instantaneous thermal pressure To: Thara Gopinath Cc: Ingo Molnar , Peter Zijlstra , ionela.voinescu@arm.com, Vincent Guittot , Dietmar Eggemann , Zhang Rui , qperret@google.com, Daniel Lezcano , Viresh Kumar , Steven Rostedt , Will Deacon , Catalin Marinas , Sudeep Holla , Juri Lelli , corbet@lwn.net, LKML , Amit Daniel Kachhap , Javi Merino Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 29, 2020 at 4:06 AM Thara Gopinath wrote: > > Add architecture specific APIs to update and track thermal pressure on a > per cpu basis. A per cpu variable thermal_pressure is introduced to keep > track of instantaneous per cpu thermal pressure. Thermal pressure is the > delta between maximum capacity and capped capacity due to a thermal event. s/capped/decreased to have consistent use throughout the series e.g. in patch 1. Though personally, I like "capped capacity" in which case s/decreased/capped in patch 1 and elsewhere. > > topology_get_thermal_pressure can be hooked into the scheduler specified > arch_cpu_thermal_capacity to retrieve instantaneous thermal pressure of a > cpu. > > arch_set_thermal_pressure can be used to update the thermal pressure. > > Considering topology_get_thermal_pressure reads thermal_pressure and > arch_set_thermal_pressure writes into thermal_pressure, one can argue for > some sort of locking mechanism to avoid a stale value. But considering > topology_get_thermal_pressure can be called from a system critical path > like scheduler tick function, a locking mechanism is not ideal. This means > that it is possible the thermal_pressure value used to calculate average > thermal pressure for a cpu can be stale for upto 1 tick period. > > Signed-off-by: Thara Gopinath > --- > > v6->v7: > - Changed the input argument in arch_set_thermal_pressure from > capped capacity to delta capacity(thermal pressure) as per > Ionela's review comments. > > arch/arm/include/asm/topology.h | 3 +++ > arch/arm64/include/asm/topology.h | 3 +++ Any particular reason to enable this for arm/arm64 in this patch itself? I'd have enabled them in two separate patches after this one. > drivers/base/arch_topology.c | 11 +++++++++++ > include/linux/arch_topology.h | 10 ++++++++++ > 4 files changed, 27 insertions(+) > > diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h > index 8a0fae9..3a50a19 100644 > --- a/arch/arm/include/asm/topology.h > +++ b/arch/arm/include/asm/topology.h > @@ -16,6 +16,9 @@ > /* Enable topology flag updates */ > #define arch_update_cpu_topology topology_update_cpu_topology > > +/* Replace task scheduler's default thermal pressure retrieve API */ > +#define arch_cpu_thermal_pressure topology_get_thermal_pressure > + > #else > > static inline void init_cpu_topology(void) { } > diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h > index a4d945d..a70896f 100644 > --- a/arch/arm64/include/asm/topology.h > +++ b/arch/arm64/include/asm/topology.h > @@ -25,6 +25,9 @@ int pcibus_to_node(struct pci_bus *bus); > /* Enable topology flag updates */ > #define arch_update_cpu_topology topology_update_cpu_topology > > +/* Replace task scheduler's default thermal pressure retrieve API */ > +#define arch_cpu_thermal_pressure topology_get_thermal_pressure > + > #include > > #endif /* _ASM_ARM_TOPOLOGY_H */ > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index 6119e11..68dfa49 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -42,6 +42,17 @@ void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity) > per_cpu(cpu_scale, cpu) = capacity; > } > > +DEFINE_PER_CPU(unsigned long, thermal_pressure); > + > +void arch_set_thermal_pressure(struct cpumask *cpus, > + unsigned long th_pressure) > +{ > + int cpu;