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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1ED1AC433F5 for ; Thu, 3 Feb 2022 18:57:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353626AbiBCS5i (ORCPT ); Thu, 3 Feb 2022 13:57:38 -0500 Received: from mail-yb1-f170.google.com ([209.85.219.170]:36807 "EHLO mail-yb1-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234035AbiBCS5h (ORCPT ); Thu, 3 Feb 2022 13:57:37 -0500 Received: by mail-yb1-f170.google.com with SMTP id c6so11869277ybk.3; Thu, 03 Feb 2022 10:57:36 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EpyDkyG4xB8jSiDotXaela/62CttDlFOZPwhGEx9NZw=; b=eb94PvEyfTUZtS9bR7I5hbXxYxFSc+FuwSLv0LbhFds/KTd+1sFuhAKrMtJmt0u+Fv kW+s3ZATGz9Qzyo5g6jdM3ITINRyMjLbI+ltFaGQIeHCqhxy1vUZCS/qiLwrWq+hO2e2 Bz8KVGpVqJ6AKZueZcpanNiy7AKGo9sSYYb3ONRQ84R/CJJjR9AXBYbU04m1d/XnmwqX WNbLLL+3mxTD3xZcndxoWf2gSk1uuHFB6yKmcc1Kq9PJEL/S3p4fJE3KbYD/dKARfPrE tghjo5UBIvAblJDifjQQFgYpLlCdtu2LOJSH843mhyGEE3syYwaeLE/m/2/ByP78zn7V kmRA== X-Gm-Message-State: AOAM531nmNmkeR0BHVl1TeXefB6EWU/jLbzgTvf5pO2O+0QnNf4fRorG Cn1x0VU/zbEyMkBVUbx9nK/MrrMxII8uwfwPN69SlapF X-Google-Smtp-Source: ABdhPJz0kFA/+2Su2AVIgcBW2zIragRHga6XXbhsgGUI/eIIrqm+rIyx8I+hh8apo+8f+MITfnz7WjBPV4hP3PVweK4= X-Received: by 2002:a0d:d782:: with SMTP id z124mr5513446ywd.28.1643914656415; Thu, 03 Feb 2022 10:57:36 -0800 (PST) MIME-Version: 1.0 References: <20220127193454.12814-1-ricardo.neri-calderon@linux.intel.com> In-Reply-To: From: "Rafael J. Wysocki" Date: Thu, 3 Feb 2022 19:57:25 +0100 Message-ID: Subject: Re: [PATCH v5 0/7] Thermal: Introduce the Hardware Feedback Interface for thermal and performance management To: Ricardo Neri Cc: "Rafael J. Wysocki" , Daniel Lezcano , Linux PM , "the arch/x86 maintainers" , "open list:DOCUMENTATION" , Len Brown , Srinivas Pandruvada , Aubrey Li , Amit Kucheria , Andi Kleen , Tim Chen , Lukasz Luba , "Ravi V. Shankar" , Ricardo Neri , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 30, 2022 at 4:23 PM Rafael J. Wysocki wrote: > > On Thu, Jan 27, 2022 at 8:33 PM Ricardo Neri > wrote: > > > > Hi, > > > > This is v5 of this patchset after having incorporated the feedback from > > reviewers. Please find v1, v2, v3, and v4 in [1], [2], [3], and [4], > > respectively. > > > > The Intel Hardware Feedback Interface (HFI) [5] provides information about > > the performance and energy efficiency of each CPU in the system. It uses a > > table that is shared between hardware and the operating system. The > > contents of the table may be updated as a result of changes in the > > operating conditions of the system (e.g., reaching a thermal limit) or the > > action of external factors (e.g., changes in the thermal design power). > > > > The information that HFI provides are specified as numeric, unit-less > > capabilities relative to other CPUs in the system. These capabilities have > > a range of [0-255] where higher numbers represent higher capabilities. > > Energy efficiency and performance are reported in separate capabilities. > > If either the performance or energy capabilities efficiency of a CPU are 0, > > the hardware recommends to not schedule any tasks on such CPU for > > performance, energy efficiency or thermal reasons, respectively. > > > > The kernel or user space may use the information from the HFI to modify > > task placement and/or adjust power limits. This patchset focuses on the > > user space. The thermal notification framework is extended to relay > > updates of CPU capacity. Thus, a userspace daemon can affinitize workloads > > to certain CPUs and/or offline CPUs whose capabilities are zero. > > > > The frequency of HFI updates is specific to each processor model. On some > > systems, there is just a single HFI update at boot. On other systems, there > > may be updates every tens of milliseconds. In order to not overwhelm > > userspace with too many updates, they are limited to one update every > > CONFIG_HZ jiffies. > > > > Thanks and BR, > > Ricardo > > > > [1]. https://lore.kernel.org/lkml/20211106013312.26698-1-ricardo.neri-calderon@linux.intel.com/ > > [2]. https://lore.kernel.org/lkml/20211220151438.1196-1-ricardo.neri-calderon@linux.intel.com/ > > [3]. https://lore.kernel.org/lkml/20220106025059.25847-8-ricardo.neri-calderon@linux.intel.com/ > > [4]. https://lore.kernel.org/lkml/20220108034743.31277-1-ricardo.neri-calderon@linux.intel.com/ > > [5]. https://www.intel.com/sdm > > > > Changes since v4: > > ++ Unchanged patches: 1, 2. > > * Reworded description hfi_instance::hdr and hfi_instance::data. > > (Patch 3; Srinivas) > > * Call intel_hfi_online() before enabling the thermal vector at the > > local APIC is enabled. This makes sure that a CPU has an associated > > HFI instance when an HFI event happens. Reworded the commit message to > > reflect this change. (Patch 4; Srinivas) > > * Set hfi_instances to NULL if we fail to allocate memory for > > hfi_instance::cpus. (Patch 4; Srinivas) > > * Delayed initialization of local variables until after the check for a > > non-NULL hfi_instances in intel_hfi_online(). (Patch 4; Srinivas) > > * Optimized the error path in init_hfi_init() to not needlessly > > free the memory of cpumasks that have not been allocated. (Patch 4; > > Srinivas) > > * Removed pointless checks for X86_FEATURE_HFI in > > intel_hfi_[on|off]line(). It is sufficient to check for a non-NULL > > hfi_instances or a CPU's hfi_instance. (Patch 4) > > * Added a dedicated (i.e., not system_wq) workqueue to process HFI updates. > > Reworded commit message accordingly. (Patch 5; Rafael) > > * Repurposed comment on possibly receiving an HFI event with a NULL > > hfi_cpu_info::instance. Patch 4 fixed this potential issue. Instead, > > add a debug statement. (Patch 5; Srinivas) > > * Wrapped check for NULL hfi_cpu_info::instance in the unlikely macro. > > (Patch 5; Srinivas) > > * Renamed struct cpu_capability as struct thermal_genl_cpu_caps. > > (Patch 6; Rafael) > > * Removed automatic variable ret from > > thermal_genl_event_cpu_capability_change() and instead always return > > -EMSGSIZE on error. (Patch 6; Rafael) > > * Reworked parsing of HFI capabilities into chunks of > > HFI_MAX_THERM_NOTIFY_COUNT CPUs at a time to reduce the time > > we spend with interrupts disabled. (Patch7; Srinivas) > > * Protected hfi_instance::cpus when iterating over them. (Patch 7; > > Rafael) > > All patches in the series look good to me now, so I will be queuing it > up for 5.18 unless there are any objections or concerns. The series has been applied as 5.18 material, thanks!