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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 4C875C43381 for ; Fri, 22 Mar 2019 15:00:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 127D8218B0 for ; Fri, 22 Mar 2019 15:00:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="0FE4OOn2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729484AbfCVPAW (ORCPT ); Fri, 22 Mar 2019 11:00:22 -0400 Received: from merlin.infradead.org ([205.233.59.134]:48746 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729129AbfCVPAW (ORCPT ); Fri, 22 Mar 2019 11:00:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=dYjCVcv6V5v51cbzYdQl2UO0Sx67KxhRWRVbVYjb8Wc=; b=0FE4OOn29jCGsibK0eOvjADdg V7+Yom5ubyTxHfy2Dcf2fUCVB57MT9GnPxv8DCvR4+jLz/c66LO1G2KsiJeSvp2n6O/6A0qwX7lUt hOnlCaVRhLTFV5o2NMYwOv0xKrapTpzSMvkCg2YmTWWme1gQP8YuPHWH2hNw2oRmz0dQngNLRVt8h BZSa7n1sB0/cgrF8rkrc0xBMxGVFYX89BOOsBI62kQtxWQuH9grMu3Up6UzYejV5sNuZ5jKdUY5H4 k1RKEHQle4cgznGwq6/I7WBKrILD9sio1sqpCbPTuKk16gqebqWct98l52gOJiWYAvZBaZx4Qcjuv uMfK6fHhw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h7LeU-0002Ou-W8; Fri, 22 Mar 2019 15:00:11 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 72E99287233CD; Fri, 22 Mar 2019 16:00:09 +0100 (CET) Date: Fri, 22 Mar 2019 16:00:09 +0100 From: Peter Zijlstra To: "Rafael J. Wysocki" Cc: x86 , LKML , Len Brown , Linux PM , Srinivas Pandruvada , Laura Abbott , Thomas Gleixner , Ingo Molnar , Simon Schricker , Borislav Petkov , Hannes Reinecke Subject: Re: [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs interface Message-ID: <20190322150009.GY6058@hirez.programming.kicks-ass.net> References: <1637073.gl2OfxWTjI@aspire.rjw.lan> <1762575.ER2xjzr9E1@aspire.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1762575.ER2xjzr9E1@aspire.rjw.lan> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 21, 2019 at 11:20:17PM +0100, Rafael J. Wysocki wrote: > + ret = rdmsrl_on_cpu(cpu, MSR_IA32_ENERGY_PERF_BIAS, &epb); > + if (ret < 0) > + return ret; > + > + ret = wrmsrl_on_cpu(cpu, MSR_IA32_ENERGY_PERF_BIAS, > + (epb & ~EPB_MASK) | val); That's two back-to-back IPIs and a giant waste. If you'd use a proper msr shadow variable, you'd not have to do the rdmsr_on_cpu :-)