From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F01AE2AE96; Thu, 19 Dec 2024 16:37:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734626263; cv=none; b=XUbzGzQMTgnRcxvN8D1h/RgU61Ubfb30MUpr+aQA8irN/vIKidpfY2qRZFje5zlc5IXnoGChVs5Kh5utnCf6ayGsvy4qRugkeX1wVw1/CZ1U/OgFadGK4B4yDOVYVB56ugshBSX+LGlAYA9xNhemc58LrwNc5MXHAXLEr/9QH+g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734626263; c=relaxed/simple; bh=EDefhr+82fJbRgYXE5hYeauAAvr+YHKOyCh5/nvtES8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GKs1d98vISfCDXTGDs2Q5xk+INISLfol8KtBck7W2R85TjHGXIyFUpcMm3HEVsqLRrgqUQfSS+i2BDZfoDhqrC3sgGzR0SveQf1gIic5DfvyD+KKUKYgwzS9cNKyn+LAxM+pF2Row9W7vC1WvJDsRsUxf/tqRJCMfcTZUQJPPYI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D1y9GpGu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D1y9GpGu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 30BECC4CECE; Thu, 19 Dec 2024 16:37:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734626262; bh=EDefhr+82fJbRgYXE5hYeauAAvr+YHKOyCh5/nvtES8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=D1y9GpGuL1fWahJnlbpJHQdsMRxJFEK4KZrC8kBjYXmx/0e1/SCdb29c4SxCZcWnM 55tiqWJBaClPYHQJaELNouhJILty3MQy2clsZJ3CsypktKSAUDn2KtN+6w2fKGMAo9 qTYmzXYVrYULvu3Q+W2apG9Kk/ecYfJ/DetIv9STDugdAak61GdBDQYL06qHnCWdUI jt5qiKFB6CKlF4ja7JTsthcxeF2NYpMMyWfzsP+ZcPnXRqpIDENiTJSWytTRZTCMNF 1m4iMbb2lLn8x4L+iFtlc+bUFK+lRbStGdpzXxEkhgtOlBMdr/RLFuHZBXu05aQ70g cUcSvhd1mifXQ== Date: Thu, 19 Dec 2024 16:37:37 +0000 From: Will Deacon To: =?utf-8?Q?Miko=C5=82aj?= Lenczewski Cc: ryan.roberts@arm.com, catalin.marinas@arm.com, corbet@lwn.net, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev Subject: Re: [RESEND RFC PATCH v1 5/5] arm64/mm: Elide tlbi in contpte_convert() under BBML2 Message-ID: <20241219163736.GG24724@willie-the-truck> References: <20241211160218.41404-1-miko.lenczewski@arm.com> <20241211160218.41404-6-miko.lenczewski@arm.com> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241211160218.41404-6-miko.lenczewski@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) On Wed, Dec 11, 2024 at 04:01:41PM +0000, MikoĊ‚aj Lenczewski wrote: > If we support BBM level 2, we can potentially avoid an intermediate > TLB invalidation, as hardware is capable of managing the TLB itself > in this situation. Hardware will either silently clear out the > offending entry, or will take a TLB Conflict Abort Exception. > > Note that such aborts should not occur on Arm hardware and indeed > were not seen on any of the benchmarked systems. > > Eliding the invalidation results in a 12% improvement on a > microbenchmark which targeted the worst case of contpte_convert(), which > represents an 80% reduction in the overhead of contpte_convert(). Can you run something more indicative of real world performance than a targetted microbenchmark please? Will