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 6A308E77184 for ; Thu, 19 Dec 2024 16:39:02 +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-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=4DEtOl5S+zY+lZKEyqIrjSVPMuNdu+YZJg2TbuGdqk4=; b=K0X1eDbDdsSEUcBP1TP4zgmpej XTJhUDuQl0M9GLjWsJqO+4WaKXp3sZ1X6PJg/ARSMEZput9W1kdBfMzLK77BJjn4DqRJEj6y9lDWv tOqGejpTMYGiJGabxuRGqMGHVWbzlE4Gb0O37LrMSJaUhfRNESTVa5ylcL7r0Lw18qyEMOWGAoaDi nMzp4O5LgWV6xpEOgpktS/L329InNneFuBIyfHjMcv0vpiXlC5LqanY4qqJsCVvS/Tt2WBLSH33Ke Rb2Fpu6DRx1wKHCvyg/bGKgF3g4VhrnJCfsxlFupw8rJcX+HbBfOdiNhfX0NMT8d/VR9CL51qtjmH +y7Sx/xg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tOJY2-00000002Nyy-3tOB; Thu, 19 Dec 2024 16:38:50 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tOJWx-00000002NoV-15Ho for linux-arm-kernel@lists.infradead.org; Thu, 19 Dec 2024 16:37:44 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id BFF775C58E0; Thu, 19 Dec 2024 16:37:00 +0000 (UTC) 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> 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) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241219_083743_338755_52AD5230 X-CRM114-Status: UNSURE ( 9.71 ) X-CRM114-Notice: Please train this message. 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 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