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 6622F2D8DD9 for ; Wed, 18 Feb 2026 13:29:51 +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=1771421391; cv=none; b=oZ2rHEjOS73bq9RwrzYlg1zlANDokHK2hJkoh5wXGFIxp3/aUSlFUZXSqPAzvM6WXYB3kLzXENsp+871B/4djF3SD7O/3kDhL+naaNdINXtsvg+wZsnrJPAt+zFfvObcmWYWOOdczqC/338HpdKsAHJBWAQYEiJp6Edg+DRDnKY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771421391; c=relaxed/simple; bh=sKKUJ4hpt7H3ThiktsCgA+vUzyYvf+FASOjdc2KrzCE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kdF4LAx3voq4QmQTCj6lNW060/zPv2UAH3JE4sofO1L0PxnfP3aDHBy+Y3CXFx7ajRE5PE+MSw30+0Fur1xAc3rXE1y0vg8O9DCGR3hy7LVVPrsHsLFINaybL6ieW4Ixp8Sq5tILY6aGSHnXU3ibIv5yP0XzBn+L5hc6eO7S+JQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=c0wqFhLS; 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="c0wqFhLS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91126C19421; Wed, 18 Feb 2026 13:29:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771421391; bh=sKKUJ4hpt7H3ThiktsCgA+vUzyYvf+FASOjdc2KrzCE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=c0wqFhLSzumL/OqPVbXtDtiizPalO/h0r5DGPjU7oar+NwxCyFoB85yznz0RpcjbV oOVPNlCz8+BYqDNziaw7p+V/YPTFeBTHdq7QmA0xvLJhQmy391sXlptl/YwqBg1yFy ygBkaBxZCYX4+wckU7C7SGe2N+4/4NSVzyY8ogVzeCJBZ7c9NaTjlhhhvzdpo+oO32 nqTTdSy4BBbNZXaf6fE22dGE4qb6NkQoshHQ7GqKmP0U9elaVKCEjLr9E6IcedI9Rs DsEmNQG74Gg1n1Uu19FekKfzihoMfHu92RORquyyl8bif1R5AojphHltIwTTQwq8QY r4y21ZPFq0CUQ== Message-ID: Date: Wed, 18 Feb 2026 14:29:44 +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 > int main(int argc, char **argv) > { > int i, j, ret; > long long k; > > if (argc < 4) { > printf("USAGE: %s region_size_kib region_count iterations\n", argv[0]); > printf("Creates multiple regions and times mprotect() calls\n"); > return 1; > } > > long region_size = atol(argv[1]) * 1024L; > int region_count = atoi(argv[2]); > int iterations = atoi(argv[3]); > > int pagesize = sysconf(_SC_PAGESIZE); > > vchar_t **regions = malloc(region_count * sizeof(vchar_t*)); > if (!regions) { > perror("malloc"); > return 1; > } > > for (i = 0; i < region_count; i++) { > regions[i] = (vchar_t *) mmap(NULL, region_size, > PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0L); > I assume that the regression might be more pronounced with MAP_SHARED, because there we really didn't ever required the page/folio during mprotect() IIRC. -- Cheers, David