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=0.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_DBL_ABUSE_MALW,USER_AGENT_SANE_1 autolearn=no 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 243E2C2D0DB for ; Thu, 30 Jan 2020 15:33:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E76B02082E for ; Thu, 30 Jan 2020 15:33:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MAARS36Y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E76B02082E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=VaNdtxLkQzhBJssw1tkEH9RCW7Q9fv2fAl6EXFcF9xw=; b=MAARS36Yt8yDR6 44fF9GQpaKg+CWmu5OMxQURsPAKIM8gBFQndi0CXsTdglEfe995AGuziB66RuPX1zwUxqFQg+mF+J To71o2OFExdcmfBaaFnaEeav4IVHhflK4CVigY4WdzmKBBr4Ok6erJdH//TBqTVAqCJcsblAJeDRA QEaiQfwxrxxk7WnNaoV2ySyKmgLifTWisT1qJRKUFQDcQnqarC0xOmJEp4hdLOQBqWEILEjYwPPKC rtC8JJ3ALb2L/9KiFigQYDYobv0YZuu8Azz8sDAKqPH5uyKk3N5yfJWh+Qq4E9mfJkxwtUtqPik9m FlrGhaU+hcu/4i3i5isg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ixBoz-00020C-Iv; Thu, 30 Jan 2020 15:33:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ixBov-0001yH-Pd for linux-arm-kernel@lists.infradead.org; Thu, 30 Jan 2020 15:33:31 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 838EB31B; Thu, 30 Jan 2020 07:33:27 -0800 (PST) Received: from localhost (unknown [10.1.198.81]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 24FC23F68E; Thu, 30 Jan 2020 07:33:27 -0800 (PST) Date: Thu, 30 Jan 2020 15:33:25 +0000 From: Ionela Voinescu To: Peter Zijlstra Subject: Re: [PATCH v2 5/6] TEMP: sched: add interface for counter-based frequency invariance Message-ID: <20200130153325.GA5208@arm.com> References: <20191218182607.21607-1-ionela.voinescu@arm.com> <20191218182607.21607-6-ionela.voinescu@arm.com> <20200129193741.GU14914@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200129193741.GU14914@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200130_073329_877183_F67714FA X-CRM114-Status: GOOD ( 16.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, maz@kernel.org, Juri Lelli , suzuki.poulose@arm.com, catalin.marinas@arm.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, ggherdovich@suse.cz, sudeep.holla@arm.com, will@kernel.org, dietmar.eggemann@arm.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wednesday 29 Jan 2020 at 20:37:41 (+0100), Peter Zijlstra wrote: > On Wed, Dec 18, 2019 at 06:26:06PM +0000, Ionela Voinescu wrote: > > To be noted that this patch is a temporary one. It introduces the > > interface added by the patches at [1] to allow update of the frequency > > invariance scale factor based on counters. If [1] is merged there is > > not need for this patch. > > > > For platforms that support counters (x86 - APERF/MPERF, arm64 - AMU > > counters) the frequency invariance correction factor can be obtained > > using a core counter and a fixed counter to get information on the > > performance (frequency based only) obtained in a period of time. This > > will more accurately reflect the actual current frequency of the CPU, > > compared with the alternative implementation that reflects the request > > of a performance level from the OS through the cpufreq framework > > (arch_set_freq_scale). > > > > Therefore, introduce an interface - arch_scale_freq_tick, to be > > implemented by each architecture and called for each CPU on the tick > > to update the scale factor based on the delta in the counter values, > > if counter support is present on the CPU. > > > > Either because reading counters is expensive or because reading > > counters from remote CPUs is not possible or is expensive, only > > update the counter based frequency scale factor on the tick for > > now. A tick based update will definitely be necessary either due to > > it being the only point of update for certain architectures or in > > order to cache the counter values for a particular CPU, if a > > further update from that CPU is not possible. > > > > [1] > > https://lore.kernel.org/lkml/20191113124654.18122-1-ggherdovich@suse.cz/ > > FWIW, those patches just landed in tip/sched/core Thanks, Peter, I'll drop this one next time around. Ionela. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel