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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B589DC49EA1 for ; Tue, 6 Aug 2024 23:00:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=czRgRDeRzLrqBrQivBvizwUbT0h+w1TNXUGWQtXg8MQ=; b=v6UBg9WgxXgo2iJ4J2wzd0b2/M g/f5oHsecgU9p+VaTOKpdFMfzKHnLd6iYdcSTpVRspfW6bC4b1uyFxP2qNtJ5BmZKTVuap4PX4Gu8 06zn6fkTB5/uPJqbFYtvg4ZdMbx1VyIlgitswPRrnoPTKXxx7ySwQiZ8Sn4GNuiw44bJJiv7DXycg 8sPdYEa3Z4Gs1ZuyNBN8LXA20wejLleqFiwIomZP4N45LCjZWO2hpG6MGOSV2inmk2qh4oVg1SlgU tObxJmsEuVoP4B0irZkzBy8+uQElateyG7bsFuZLkpx2AHzIi4EqDxX1svFZLjkXhUOkxqjGMHcun 3z4jw3mw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sbTAY-00000003EbP-3ylK; Tue, 06 Aug 2024 23:00:42 +0000 Received: from out-183.mta0.migadu.com ([2001:41d0:1004:224b::b7]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sbT9Q-00000003EKt-3NIf for linux-arm-kernel@lists.infradead.org; Tue, 06 Aug 2024 22:59:35 +0000 Date: Tue, 6 Aug 2024 15:59:26 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1722985170; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=czRgRDeRzLrqBrQivBvizwUbT0h+w1TNXUGWQtXg8MQ=; b=t9OqXWrr8NixYPqY6nc80jW99/6NeLrV2HCWr6yUBunDx7UPLELnjrVzzN4qoVfPhsxF6V L6OSjGitosA6JNlL/hEacVd+VrB9M1fL3dtNs6ZO646Z7Wh8G5DUU5Z+ZEnbcF90hyMc3C hjA1wKcVQKSff/vgqIJ2ORksr/t65Uc= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Sean Christopherson Cc: Marc Zyngier , Paolo Bonzini , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Steve Rutherford Subject: Re: [PATCH 0/2] KVM: Protect vCPU's PID with a rwlock Message-ID: References: <20240802200136.329973-1-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240802200136.329973-1-seanjc@google.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240806_155933_099670_51D0FA8E X-CRM114-Status: GOOD ( 11.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 02, 2024 at 01:01:34PM -0700, Sean Christopherson wrote: > Protect vcpu->pid with a rwlock instead of RCU, so that running a vCPU > with a different task doesn't require a full RCU synchronization, which > can introduce a non-trivial amount of jitter, especially on large systems. > > I've had this mini-series sitting around for ~2 years, pretty much as-is. > I could have sworn past me thought there was a flaw in using a rwlock, and > so I never posted it, but for the life of me I can't think of any issues. > > Extra eyeballs would be much appreciated. Besides the nitpicks: Acked-by: Oliver Upton -- Thanks, Oliver