From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A172380026 for ; Tue, 23 Jan 2024 17:25:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706030736; cv=none; b=WKawH63J0p1mtHSplT7OOkp/uX3XhO+boBWFBicbuAZcV/NTJc1SdQBPyAd0eCAjKt2Ttsi6YmfV+bBVUxQJy65u8M/5HRhEmEtjv0EQFwr3fINRBqx5JkmGa1dqqo7Q4nNKf0x2o6fNTMz+Ooa+supy6y+4fJ8q7hv2S5VAsSo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706030736; c=relaxed/simple; bh=RlyFkbNTSdgtepfgjRlfah2drYHFWjCbQEDIFZfB0Ok=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MiAXFyiLA+k4HZYk+tamu8KpyRyjcf86c6Ndf5gqEvS6k1fDkeiY2+3ZSRG39gxahbLL6rvwxLczqjnVvd3zCF9vZ5GQhc5oyd3YMFOsKeLyF+MB6ABqocWsOv9sC3+z2mJ1U8SUZzXEo/+uIMYpc5jdhCyF5qhwmjbhp5EPZd4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=IgE1LKcS; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="IgE1LKcS" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender: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-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Bjhb2hfzK/8i0tKZI56owzt2KGG7OFmwSuGm4x1P2gU=; b=IgE1LKcSfIHc7PJOysQSDI9e3C hk4sUUEKr51UKs1Bvg2k8X8ZunFhmWH3DahtvnfuXpMFc7SgSPvGLkqwbMK53IzfZP2S9xBwHA8py 0z8BkvLbqaNoDo3qdH1Uh3Z8yoxxIeepfkheorVEfCypvlM8r1toj4PIcQlleaoq2fo1FfMuaOxwc YG3lKqsWN7cLSCyd17HeYHkpuD7UfNrfLfodJuKEKgSa6D2DTNC4NyYkEru0CisHqpwEFPi/2AGSa crYK2F1J9b4mtzFEJ1XbW9vQ0RPDnruau/wu18s7gFZbGO9DOja8ZARQ6QnhXRTJujpRSYcA4UlcB MOOXwRHQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:42660) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1rSKWX-0002q9-2X; Tue, 23 Jan 2024 17:25:21 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1rSKWQ-00027i-Vs; Tue, 23 Jan 2024 17:25:15 +0000 Date: Tue, 23 Jan 2024 17:25:14 +0000 From: "Russell King (Oracle)" To: Yuquan Wang Cc: jiahao.os@bytedance.com, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v3 00/19] arm64 kernel text replication Message-ID: References: <20240123103509.696983-1-wangyuquan1236@phytium.com.cn> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240123103509.696983-1-wangyuquan1236@phytium.com.cn> Sender: Russell King (Oracle) On Tue, Jan 23, 2024 at 06:35:09PM +0800, Yuquan Wang wrote: > > > > After applying these patches, we tested that our business performance > > increased by more than 5% and the NUMA node memory bandwidth was more > > balanced. > > > > I have successfully applied your patches on my arm64 linux. And I could > start it with a qemu machine(virt). However, I don't know the way to test > the performance it brings to the kernel. Do you have some suggestions? Please can I make one thing utterly clear... kernel text replication in a virtual machine generally doesn't make sense unless one can setup the virtual machine to be truly NUMA. In other words, groups of CPUs with their local memory and remote-node memory having higher latency. Kernel text replication is something which solves the problem on bare metal NUMA machines where running kernel text that is located in a foreign node results in the CPU running slower than it would do if the kernel text were in its local RAM. Unless the VM is setup in exactly that way, then kernel text replication has no place in a VM, and probably would result in poorer performance. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!