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 4DBD6C433F5 for ; Tue, 4 Jan 2022 14:41:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=jSiQV9/NzoESCqlyrh3drR/Zh6XOBHtQTSHMtWL3rSM=; b=NIp8fOnX2FEdXT 8ZzJ5C6RSGXAx0tHOX1ZsJmu5VNM9NaYa5ZWpKk74KBPHiKG7+dc4tSF4ZKIpVEtTQeSAhUBIBKpC m85PT9H6aFrVuOGIq6fD783XPE7D0aqTtdifzg1654aeW4E1h00KVOqjIsr5w8O2M5ouAI+YOmf5c mC/6KBRYQpvotv4YhjEoazZM0uzOhp15DrKX7jeIs30YxAjeeuQVyr6UAZLZ0XpeANkgVKAKH3uYR T0XTRwLvDOJFhDJu239rjueYe4xb8DLkuuwKtBUj7F5GicEs8s+XVT6vtnwys35U0p2oxecley2Xc 1RXvQxrrdJcwpZGRj5cg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n4kyt-00BlBU-93; Tue, 04 Jan 2022 14:40:07 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1n4kyp-00BlAj-Sy for linux-arm-kernel@lists.infradead.org; Tue, 04 Jan 2022 14:40:05 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C00046144A; Tue, 4 Jan 2022 14:40:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35811C36AED; Tue, 4 Jan 2022 14:40:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1641307202; bh=hNauZWxTvH4RpsnhBPPrHP5HNl6Fd4EBlLcYJIrT7x0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DnlI2PXSWWbV1mGMih6JiUlmLIoa9IYefEEG+Dk1Yrp/x8J/oH8hoYj6TfF0+S/9B gV93wdNiN3NdlBxynDntY9ZE3G0mCu+jq9aRvxo3wdLzgEFiWBe786T0QQvvK9oNJn qg9ibaPLSHqn4oUeeHGcOp17n202wSMAr2ljvGQDrM6HsHulNStCTgoHGJHak7VrwL TIxUlchJq7pVyonrWDbGobibWueUNnlxWqWO3IHWwUHffJa7TerYUvlapqksGMWU6V KPEiuCPSuHReynaPxk+UtgH1BVOmsyP2eApLr980jA4XAzlNnwgtXaUiMiUE5GW8yX gL+JFvvHV5VJA== Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1n4kym-00Fvxk-7I; Tue, 04 Jan 2022 14:40:00 +0000 Date: Tue, 04 Jan 2022 14:39:59 +0000 Message-ID: <87h7ajva2o.wl-maz@kernel.org> From: Marc Zyngier To: Alexandru Elisei Cc: will@kernel.org, julien.thierry.kdev@gmail.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, suzuki.poulose@arm.com, mark.rutland@arm.com Subject: Re: [PATCH kvmtool 9/9] arm64: Add support for KVM_ARM_VCPU_PMU_V3_SET_PMU In-Reply-To: <20211115165705.195736-10-alexandru.elisei@arm.com> References: <20211115165705.195736-1-alexandru.elisei@arm.com> <20211115165705.195736-10-alexandru.elisei@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: alexandru.elisei@arm.com, will@kernel.org, julien.thierry.kdev@gmail.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, suzuki.poulose@arm.com, mark.rutland@arm.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-20220104_064004_003712_543460AC X-CRM114-Status: GOOD ( 18.22 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 15 Nov 2021 16:57:05 +0000, Alexandru Elisei wrote: > > The KVM_ARM_VCPU_PMU_V3_CTRL(KVM_ARM_VCPU_PMU_V3_SET_PMU) VCPU ioctl is > used to assign a physical PMU to the events that KVM creates when emulating > the PMU for that VCPU. This is useful on heterogeneous systems, when there > is more than one hardware PMU present. > > The assumption that is made in the implementation is that the user will > pin the kvmtool process on a set of CPUs that share the same PMU. This > allows kvmtool to set the same PMU for all VCPUs from the main thread, > instead of in the individual VCPU threads. May I suggest a slightly different use model? Ideally, you'd be able to run the vcpu threads on the CPUs matching the PMU affinity, and leave all the other threads to roam on other CPUs. With your implementation, the whole of kvmtool gets stuck to a given CPU type, which can be problematic. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel