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 AC1EC2ED846 for ; Tue, 27 Jan 2026 11:39:25 +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=1769513965; cv=none; b=sE/PtgcjWRaeIUQCP+qT7S7mitP8vLf4Lv+imL+sGePPEcH2f7ia1/krU0zbth/Z46+OUbKs1MEqCSpcXMaAuIFF/Yc/A5FNMGPnJU16olcPY325KAWowc2Rgg38cvOLI/ekFu/tKqnQrHAKRblu64eY3EbW4/BDIZEMYT8JFxA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769513965; c=relaxed/simple; bh=RuTomhlbNE9tBHH5bdeCjMNZHDz/SnjRSVcc7LFJTiI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=GTa63epkKIB1unSrWYC6uNDVrmYAAO4G7MvOYTl5b+34KYbJ/hcVY/kfSkpGKFMSXSwe6SyLW0Ptc9SV1/Yex3afc0WXSKawxLqWDshPYd7OAU9MVLesByM8cu6goIP1J4fW8dA4DcZS+/aDrbay8lPcCFijXjUbvAwkEmnbrJI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VKDKQm5t; 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="VKDKQm5t" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A755DC116C6; Tue, 27 Jan 2026 11:39:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769513965; bh=RuTomhlbNE9tBHH5bdeCjMNZHDz/SnjRSVcc7LFJTiI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VKDKQm5tcxoG0eC6u8El+eWvTeznxANYk96mRGy16wkp3ue+ip+NFqnL1DdjHOT9D ImjyVVkt4bm7vqdrQpsrSBy6JVrjXvy8Ol/ko67FTbQ5Hv57Rksst/Pv1vTX1strSg 3VaJLp1iGsBqSLMDDgXMed9M3sZlDr95QwNNK+0j6Dbw9R1iYEDFhhE4tufKXADU90 uhtob+OjHZiyeggRW3JukM6BHXdLPVzNEbVyB/QuZKExyGti6IjXTOwKgqeHQ+ydic x9R1DRgTF9VV92qgdtUS52Cdg8kbSxWwkW1oR7I0wQnIybsLwFNMVhAEvgOClI3ohM uEuM6ijW7KsBA== From: Will Deacon To: Catalin Marinas , Carl Worth Cc: kernel-team@android.com, Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Taehyun Noh Subject: Re: [PATCH v2 0/2] arm64: mte: Improve performance by explicitly disabling unwanted tag checking Date: Tue, 27 Jan 2026 11:39:09 +0000 Message-ID: <176951239741.2185302.14847899262435443119.b4-ty@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251030-mte-tighten-tco-v2-0-e259dda9d5b3@os.amperecomputing.com> References: <20251030-mte-tighten-tco-v2-0-e259dda9d5b3@os.amperecomputing.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="utf-8" Content-Transfer-Encoding: 8bit On Thu, 15 Jan 2026 15:07:16 -0800, Carl Worth wrote: > [Thanks to Taehyun Noh from UT Austin for originally reporting this > bug. In this cover letter, "we" refers to a collaborative effort > between indiviuals at both Ampere Computing and UT Austin.] > > We measured severe performance overhead (25-50%) when enabling > userspace MTE and running memcached on an AmpereOne machine, (detailed > benchmark results are provided below). > > [...] Applied TCMA1 patch to arm64 (for-next/cpufeature), thanks! [2/2] arm64: mte: Set TCMA1 whenever MTE is present in the kernel https://git.kernel.org/arm64/c/a4e5927115f3 Cheers, -- Will https://fixes.arm64.dev https://next.arm64.dev https://will.arm64.dev