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 A54CCC433F5 for ; Tue, 22 Mar 2022 16:40:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239190AbiCVQmU (ORCPT ); Tue, 22 Mar 2022 12:42:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233894AbiCVQmR (ORCPT ); Tue, 22 Mar 2022 12:42:17 -0400 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF8435DE70 for ; Tue, 22 Mar 2022 09:40:49 -0700 (PDT) Received: by mail-pj1-x1036.google.com with SMTP id bx5so16082072pjb.3 for ; Tue, 22 Mar 2022 09:40:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=o3rpaN/qyinfx9+vbmrN+Nl3xvluf+KWJ9u60Df0dI0=; b=QhaVfmthOFvJjSrnWlkog3LBOWRKOE36iBal/RBM71veF92SS3i5KnHz09/P354ZWl fzZJegvx2igVgWyTDdzPNJPxnH3+dhp2x8jpjI0oLC8pfAEX6K14bnrBoT+m4n1oJFD7 kraI8Tb2fWil7TAnlhEZty7Eq5EogL6rWBY6ai6C0thn2u1RMXpkIAezO6NPTzHLpTKM +Guy7ANft5u6Q2/HVwiOwHTsdg7qMSXEfPn9wQnphf1cG3iYOe6gARQh343YvhJsDwq4 CseUA33ciulReM9O2aG9iEMav/WgwqR/AMZL0QMBu9oWL5L2H1bvyrPuecz5TcOsBevg PrXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=o3rpaN/qyinfx9+vbmrN+Nl3xvluf+KWJ9u60Df0dI0=; b=phkraV1KVMbkAfU22hjEjUldGtcQDJQjD+ws2AXETeS3I/4esqNlHS0FXVM6Bk1IaJ fG6GigV8p9BCwPmTDx7KiHsyM6PNNNeCRfORjYUKXpdeCN2DuzWxF9AOzPqyI8nx3zKf 1ib+WYe/YjwRkNsOIyYebex1Z6LuyAemuuALncceERw8oU4t90EELQNpoM9y0CMGxmen Ev1bfWada4eSK3EBA0UFYH0by7Vhy+sqn0DURFSi7aruEp0DY1D/gWSSJ0e/oTEGHcq0 ScDSO6s/QhQlrjTEhx4nkIPt/BAvrx+gZl2t+vBGNGADSOo91hP5OGafr00jocMdKelb dOsA== X-Gm-Message-State: AOAM533W8MfFOoFWxHgv2e1a3JV6iAWCMPECsA5iR1h2LPcyHqVF5tfJ fViCF0DKAWa3YCuijFlvsRk= X-Google-Smtp-Source: ABdhPJw+ZSxglIa59oM8dqp+OvB4VBQJBGSRrgGNAwPsoMOLR6fskYHNekuYghYCFY+cDr/NQCbZ3A== X-Received: by 2002:a17:90b:4b0e:b0:1c6:f499:1cc9 with SMTP id lx14-20020a17090b4b0e00b001c6f4991cc9mr6043138pjb.133.1647967248925; Tue, 22 Mar 2022 09:40:48 -0700 (PDT) Received: from localhost (2603-800c-1a02-1bae-e24f-43ff-fee6-449f.res6.spectrum.com. [2603:800c:1a02:1bae:e24f:43ff:fee6:449f]) by smtp.gmail.com with ESMTPSA id e11-20020a63e00b000000b0037341d979b8sm17860051pgh.94.2022.03.22.09.40.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Mar 2022 09:40:48 -0700 (PDT) Sender: Tejun Heo Date: Tue, 22 Mar 2022 06:40:46 -1000 From: Tejun Heo To: Vincent Guittot Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, linux-kernel@vger.kernel.org, parth@linux.ibm.com, qais.yousef@arm.com, chris.hyser@oracle.com, pkondeti@codeaurora.org, Valentin.Schneider@arm.com, patrick.bellasi@matbug.net, David.Laight@aculab.com, pjt@google.com, pavel@ucw.cz, dhaval.giani@oracle.com, qperret@google.com, tim.c.chen@linux.intel.com Subject: Re: [RFC 6/6] sched/fair: Add sched group latency support Message-ID: References: <20220311161406.23497-1-vincent.guittot@linaro.org> <20220311161406.23497-7-vincent.guittot@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue, Mar 22, 2022 at 05:10:36PM +0100, Vincent Guittot wrote: > latency_nice is quite similar to nice. The nice latency is used as an > index to get a latency weight in the range [-1024:1024]. latency_nice > is in the range [-20:19] and latency_prio shifts it in the range > [0:40] . This index is then used to get the latency weight similar to > how the nice prio is used to get a weight. That being said, the > latency should probably reflect the latency_weight instead of the > latency_prio in order to be aligned with the weight and weight.nice > fields of cgroups. > > As described in patch 5 commit message, the weight is then used to > compute a relative offset to check whether the waking task can preempt > the current running task. So, what I'm trying to say is if it is actually a weight, just use weight values instead of arbitrary mapped nice values. Nobody can tell how the latency nice value of -2 compares against, say, 3. If you can define it clearly in terms of weights (or something else clearly describable), it'd be a lot better. Thanks. -- tejun