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 1E3AD1EB5E1 for ; Fri, 13 Feb 2026 15:47:36 +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=1770997656; cv=none; b=l+1fj1XFCeGO7aPGdBVV+7dZ694s+1X2pmZVTuRnkIl3UTUn8RJ2XKigJVsrogso+muNkrf1lSGBf8EBXde4dRpp9RXDkD4NvMOq4wKaHQfUfV1IeZGEs90MbNMIgROkIR6q+2bPp40EPDFIhvQUuK2gxTaczoDhGkVvWM51lNs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770997656; c=relaxed/simple; bh=XfS2U8kOK3udT3K8Q+XXE1402dkA/o2Hbuihs3yn/YE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jb8fDSBndWeLkkmT/bxiBk19CO3+DO1QATFaMfRB+7nDiobr1q56zVBUQ9w/o2PRWntPMP1Vshy0wWVTDdLODmL+Ss0VThvTdcbr8Af4stYSWX1nHZWDxL/72Udp/wBJDAwn/IcgLcJW5zjuyTJEq/dsjva80hrHTqckeJ2ki60= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E1q0w0cD; 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="E1q0w0cD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C19BC116C6; Fri, 13 Feb 2026 15:47:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770997655; bh=XfS2U8kOK3udT3K8Q+XXE1402dkA/o2Hbuihs3yn/YE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=E1q0w0cDwPhOB4LOSqfrUxeF5HN6B0FfC17poneLeKRwHBfHScquG3UD203zHqHjP Qdhqz0Ctjr1uFF/kXy6c+yP8JKhLJ6Ml+n1lHcsu85oCiL9wE7JRHZCHZLhVSwxYoJ xtzWwG7bm+gXJudcH/2V8Ebt/ixxX+OUI8d8Y2kehEBlV2mOTLHqa5fWa00cj7xPkR pdsYcyoULcTrFKrLoBBlCo841df4RR4dO0ETVGv/Osfz0dlW+TVxl70sQLFoljnFRj UE/YVpqYUgDaNVbdyDII+6taRrOJys0/+KcS33CEgCcwslbkpIx9NfhK7QKGUZQvMc 3A5JqaribBaPw== Message-ID: Date: Fri, 13 Feb 2026 16:47:29 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REGRESSION] mm/mprotect: 2x+ slowdown for >=400KiB regions since PTE batching (cac1db8c3aad) To: Luke Yang , dev.jain@arm.com Cc: jhladky@redhat.com, akpm@linux-foundation.org, Liam.Howlett@oracle.com, willy@infradead.org, surenb@google.com, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/13/26 16:08, Luke Yang wrote: > Hello, Hi! > > we have bisected a significant mprotect() performance regression in > 6.17-rc1 to: > > cac1db8c3aad ("mm: optimize mprotect() by PTE batching") > > The regression becomes clearly visible starting around 400 KiB region > sizes and above. It is also still present in the latest 6.19 kernel. > Micro-benchmark results are nice. But what is the real word impact? IOW, why should we care? -- Cheers, David