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 D02D928D857 for ; Fri, 11 Apr 2025 09:21:44 +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=1744363304; cv=none; b=kY/ELPvtCJUXyT4YYOLAy3nyQorQ6E4oA0z7EYozqzynKVdenPrIibbZkoMal4gcf/p8RvafF7S2t7jO1iZsYGDIfbb6p6D/u07pbHZ3UldbJUIS7KaSKK+lJNpZzZ6J35+I8AbW7PeFySxX06EzINenX6n8b4DU6PU0+Fwggf0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744363304; c=relaxed/simple; bh=TU38Yz0wslbhAhgiT67MgDKR2lBijTLSXefhthfuYAI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=h7supgekAzAYTm8b5TRg+0a+CKgliI0G/3o4+Fub6i15pIbcgkKwwcUCMxboXn3zamFkISgF0ZRxH170YniX9Vo6mEKBT6faAMrIxaJF6QnKmORBmwGxnFRSmqe5bA/Ae6yBYZejK5AGzCW4EP+FA92UeuGnQvvraMSOnVz9H+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SjXHwmnM; 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="SjXHwmnM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61A46C4CEE2; Fri, 11 Apr 2025 09:21:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744363304; bh=TU38Yz0wslbhAhgiT67MgDKR2lBijTLSXefhthfuYAI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SjXHwmnMOpa/T9EDIGZIX3IDPYF02ahzYO+YFFts9WBT9LzVU+sYE7lMFunEOQ6jC i3wle5PIGi0XEF7KoFSrobsHG4iLPceRLhg3C6GU3Ry3UNp7hkKNQcQYQ/s4/NLn+3 Q0EFYQ0FW4/p5igzjZmcqVsIOYDmArkMmLPPFLrgyi5FToLl/MbdIPVJjn76QEOMPC i53dzsttNM1if0JeK0UXoTKlynDInlA6vtJAPClKBzRETPL9clMN33KrpH1gQo6+bh 5/FPJTOH4S0Pe27UzE9YpsNYeyXYnrbnG+Ca6jrZMF65hsEqwfCPUL/tiO65R1C7rW ATb6+H13FBf2A== Date: Fri, 11 Apr 2025 11:21:30 +0200 From: Ingo Molnar To: Kevin Brodsky Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , David Hildenbrand , Ira Weiny , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , Rick Edgecombe , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: Re: [RFC PATCH v4 00/18] pkeys-based page table hardening Message-ID: References: <20250411091631.954228-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20250411091631.954228-1-kevin.brodsky@arm.com> * Kevin Brodsky wrote: > Performance > =========== > > Caveat: these numbers should be seen as a lower bound for the overhead > of a real POE-based protection. The hardware checks added by POE are > however not expected to incur significant extra overhead. > > +-------------------+----------------------------------+------------------+---------------+ > | Benchmark | Result Class | Without batching | With batching | > +===================+==================================+==================+===============+ > | mmtests/kernbench | elsp-64 | 0.20% | 0.20% | > | | syst-64 | 1.62% | 0.63% | > | | user-64 | -0.04% | 0.05% | > +-------------------+----------------------------------+------------------+---------------+ > | micromm/fork | fork: p:1 | (R) 225.56% | -0.07% | > | | fork: p:512 | (R) 254.32% | 0.73% | > +-------------------+----------------------------------+------------------+---------------+ > | micromm/munmap | munmap: p:1 | (R) 24.49% | 4.29% | > | | munmap: p:512 | (R) 161.47% | (R) 6.06% | > +-------------------+----------------------------------+------------------+---------------+ > | micromm/vmalloc | fix_size_alloc_test: p:1, h:0 | (R) 14.80% | (R) 11.85% | > | | fix_size_alloc_test: p:4, h:0 | (R) 38.42% | (R) 10.47% | > | | fix_size_alloc_test: p:16, h:0 | (R) 64.74% | (R) 6.41% | > | | fix_size_alloc_test: p:64, h:0 | (R) 79.98% | (R) 3.24% | > | | fix_size_alloc_test: p:256, h:0 | (R) 85.46% | (R) 2.77% | > | | fix_size_alloc_test: p:16, h:1 | (R) 47.89% | 3.10% | > | | fix_size_alloc_test: p:64, h:1 | (R) 62.43% | 3.36% | > | | fix_size_alloc_test: p:256, h:1 | (R) 64.30% | (R) 2.68% | > | | random_size_alloc_test: p:1, h:0 | (R) 74.94% | (R) 3.13% | > | | vm_map_ram_test: p:1, h:0 | (R) 30.53% | (R) 26.20% | > +-------------------+----------------------------------+------------------+---------------+ So I had to look 3 times to figure out what the numbers mean: they are the extra overhead from this hardening feature, measured in system time percentage, right? So "4.29%" means there's a 4.29% slowdown on that particular workload when the feature is enabled. Maybe add an explanation to the next iteration? :-) Thanks, Ingo