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 D38F3C433EF for ; Fri, 8 Jul 2022 18:16:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238696AbiGHSQV (ORCPT ); Fri, 8 Jul 2022 14:16:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238630AbiGHSQV (ORCPT ); Fri, 8 Jul 2022 14:16:21 -0400 Received: from mail-qt1-x82f.google.com (mail-qt1-x82f.google.com [IPv6:2607:f8b0:4864:20::82f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 213C933E09 for ; Fri, 8 Jul 2022 11:16:20 -0700 (PDT) Received: by mail-qt1-x82f.google.com with SMTP id c20so6282171qtw.8 for ; Fri, 08 Jul 2022 11:16:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=wnKK7CshnFfIvJk8YaQeXocTj7op6NCtaSsltr31Yq8=; b=QGBu3N33pniLaKliww348mnJmQwrt0hjHNxMZkkNiWlpjhB4VJhrHuHpcdthWWYwGm WDAYML4PaTsdTez88aEEWvOqXwY3LIcYdk5gjePfPMINlUZe89PZ21UxzAW0vAKkvXN9 k3/4l0nnPhc9CZgJNy+Vh1C8lkngvLRmsdXuc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=wnKK7CshnFfIvJk8YaQeXocTj7op6NCtaSsltr31Yq8=; b=VBzA2m6w7NY5hn4gUgYu7iJP5njMmboy53QDeNY+DUzv32ML4rT/CRRr3sBQWJuAHn MCLscOPcBJDrwhSxW7RjtL2I6xtMLMkNy6gf6+Vp7r75+lvonh3fqTwxOvXfPbJSSPLZ 4mXlBX6nhr1T3410PssHHYoKUk4OjeSvKDc4/btYcPmC1XCvVCszCWW0OeukBWUVXK3h MK9Jw644x3RzLKf8EUeparaCKUdqimevimyzHVsfF+WM29zpp1GCaxNacCGfdJ0de/ix UeFN/GsvH+z56goH4T955B50Hoj6ZcRlLbnPDAZy9akq6S0HcyZDHbmc4IT/F/f3IVYQ zWXQ== X-Gm-Message-State: AJIora9B+v2dvbwKJQWtTaeY2faW6Jz9W/LsZmIEFoSNDCf7zB+wUmIj XeiDOp4nkeBnhI4tzGBab2VTUgfu5PvC9w== X-Google-Smtp-Source: AGRyM1tgspen/c7gbMKYxvlbeEHhLrTmU0M0uwj9CXaowtA8RMl5arvM8HWUZxBLLsQic5InZdGsHA== X-Received: by 2002:a05:622a:1009:b0:31a:aed5:7bc3 with SMTP id d9-20020a05622a100900b0031aaed57bc3mr4142363qte.452.1657304179222; Fri, 08 Jul 2022 11:16:19 -0700 (PDT) Received: from localhost (228.221.150.34.bc.googleusercontent.com. [34.150.221.228]) by smtp.gmail.com with ESMTPSA id i16-20020ac84f50000000b0031ea1ad6c5asm2725185qtw.75.2022.07.08.11.16.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Jul 2022 11:16:18 -0700 (PDT) Date: Fri, 8 Jul 2022 18:16:18 +0000 From: Joel Fernandes To: Alison Chaiken Cc: rcu@vger.kernel.org Subject: Re: About dynamic switch to offload/nocb on non-server Intel machines Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Alison, Nice to hear from you! > On Fri, Jul 8, 2022 at 10:19 AM Joel Fernandes wrote: > > > > Dear Paul and Frederic, > > > > Len Brown on CC provided a good idea in a meeting on using intel_pstate to > > detect if device is a server or a consumer device. > > > Robots are neither a server nor a consumer device. Please let's not > force industrial users of RT to choose between two inapt sets of > configuration options. I see your point. > > Can we perhaps use this to trigger the offload/nocb mechanisms on consumer > > devices / distros? I was thinking the dynamic offload and the "one kernel" > > work that Frederic did can be trigger from such detection. > > > > It is true userspace can do the trigger, but maybe it is better to not leave > > it to userspace so we'd save power on bad userspaces. > > > > Come to think of it, this can even be done at boot time if we can read the > > below state early enough: > > > > > intel_pstate.c demonstrates how to detect a server when ACPI is present: > > > > > > > > > > > > #ifdef CONFIG_ACPI > > > > > > > > > > > > static bool intel_pstate_acpi_pm_profile_server(void) > > > > > > { > > > > > > if (acpi_gbl_FADT.preferred_profile =3D=3D PM_ENTERPRISE_SERVER |= > > | > > > > > > acpi_gbl_FADT.preferred_profile =3D=3D PM_PERFORMANCE_SERVER) > > > > > > return true; > > > > > > > > > > > > return false; > > > > > > } > > > > > > Robotics applications often rely on fairly "big iron" that is > configured with CONFIG_CPU_FREQ_GOV_PERFORMANCE=y. Servers and > robotics are quite different use cases, so setting configuration that > would be useful for servers whenever the CPU_FREQ_GOV_PERFORMANCE is > selected would create a headache for many users. Fair enough, I had to ask... thanks, - Joel > Best wishes, > Alison Chaiken > Aurora Innovation > > > *That was a joke.