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=-4.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_NONE, URIBL_BLOCKED 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 52F1CC433DB for ; Fri, 5 Feb 2021 17:25:17 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 E0B6164FC2 for ; Fri, 5 Feb 2021 17:25:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E0B6164FC2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-ID:References:In-Reply-To:Subject:To:From: Date:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=qo21Ipev8G0/Gg2p2o3/Zr1pwPiahaWu1cw8orpbVlU=; b=qmM6FSLNsLBH+roBBWeMNCphX 2cjTtLiRNcRfja6wOjV5WNWJSHcDcMfXXdvf2I+K0RzMCMDuTPC2YX+3W0mc/tfzYusGMcSy8s7C1 lsVp40mfOJgr6/i+pZS5yphGKFcUeLgyDQUTnTzp5SXYp5qPiPVsRC77dzqjxx2xR8feDSZEtqt13 0qkKa+yZ27dUeNyfUHTvqawxu76wcdlRCIm7aXWm04917Z3wsE4zhSZL8VtLwYLGq6CcT/LNJ8MUz JV2ML52GZKQn71KB/Mpk9N/I/icITSuYo7Xyn3IPmWyGluPgBFX7yz8VZ/tigUii2CMPQbnvmqvGI 5fIhLWHcQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l84q5-0003iF-3D; Fri, 05 Feb 2021 17:24:13 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l84q2-0003hG-DZ for linux-arm-kernel@lists.infradead.org; Fri, 05 Feb 2021 17:24:11 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0059964F2A; Fri, 5 Feb 2021 17:24:08 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1l84py-00CIfT-Pi; Fri, 05 Feb 2021 17:24:06 +0000 MIME-Version: 1.0 Date: Fri, 05 Feb 2021 17:24:06 +0000 From: Marc Zyngier To: Jing Zhang Subject: Re: [PATCH] KVM: arm64: Remove redundant check for S2FWB In-Reply-To: <20210205044403.1559010-1-jingzhangos@google.com> References: <20210205044403.1559010-1-jingzhangos@google.com> User-Agent: Roundcube Webmail/1.4.10 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: jingzhangos@google.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, qperret@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210205_122410_544242_871D7E2D X-CRM114-Status: UNSURE ( 8.99 ) X-CRM114-Notice: Please train this message. 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: suzuki.poulose@arm.com, catalin.marinas@arm.com, qperret@google.com, james.morse@arm.com, linux-arm-kernel@lists.infradead.org, will@kernel.org, kvmarm@lists.cs.columbia.edu, julien.thierry.kdev@gmail.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Jing, On 2021-02-05 04:44, Jing Zhang wrote: > Remove redundant check for CPU feature S2FWB in dcache flush code > to save some CPU cycles for every memslot flush and unmapping. What CPU cycles? This is only a static branch. Can you actually measure the overhead? What does it represent in the face of a full memslot unmapping? Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel