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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F0EA5107526F for ; Thu, 19 Mar 2026 07:40:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0F38C6B041E; Thu, 19 Mar 2026 03:40:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0A50F6B0420; Thu, 19 Mar 2026 03:40:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ED60F6B0421; Thu, 19 Mar 2026 03:40:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id DBF066B041E for ; Thu, 19 Mar 2026 03:40:35 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 9113C8B88E for ; Thu, 19 Mar 2026 07:40:35 +0000 (UTC) X-FDA: 84562015230.17.769D235 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf14.hostedemail.com (Postfix) with ESMTP id B795D100005 for ; Thu, 19 Mar 2026 07:40:33 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DBereu8Z; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1773906033; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JZvTKENtcCv2cSZKl3LDo5qu3izmZZmpsJiVt93OIbw=; b=BVN6sFyhNaFS999xncwR/vyUF9T3P60tOqU764gFRXAuf3zrvrwWNczHik6zv99zoYomSI zOB8+JbHOrz5h5dFaXl6Q/0c4PAMLbZSP/YsEiXFGJSrT+/EIv5/TK/gF59kKzLXpuxGbh pzlar4xFJi0YzmrAdz7KhObUdroKQ2E= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DBereu8Z; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773906033; a=rsa-sha256; cv=none; b=MJvJbmqIjBHAUqLb/tnIhuYrC1YgyjniM3doAk0KVm90MmAhTrXh5piI8fETGlCYcBBvx0 B3SwdTe5NtcieIhwW5HHEwa8Ni8RYfumxLMJryBCEY3K16uXn8RnWUbEayADvrbkJxM6rY RsQwzSI5dohgYp2UyVb/nJZ0LA42D0c= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id C71D642AD0; Thu, 19 Mar 2026 07:40:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 13048C19424; Thu, 19 Mar 2026 07:40:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773906032; bh=kgARICWk/x9CE46a29m+2Qcl6pq7KGjzLcdjK9IrfZ4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=DBereu8ZX4zRIwgOzq6jnFRd45UKcoO6INJUpK0rgEE4H6vgNpRG/4s1bXsz/TzEv NhhbGA9liBmxUrMFHISG5m5cW7lJQfeI9iAdx5m/AWfsSfh2WZRkVplbIiRfCYTkdP ierUOwCw4r5LSLU7duyhDpXvrNn0sjiVaZ411B6CTIrMb1VIDaPT+p/zPkr3yMcaCQ 9bwBZBYT1DPzjMc3fIWcEgg21Ch8SFZA/oqIciKj2BHlMgPTAyjxTkLcNovneEk1sQ qU3HbmRBio+n/0+dj9KXiU1Fxg303ft+zsFMhMItV1OmA/jIVnW4hOm9v/eYUjF6JF NZDcyJfEazVjA== Message-ID: Date: Thu, 19 Mar 2026 08:40:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/4] arm64/mm: contpte-sized exec folios for 16K and 64K pages To: Usama Arif , ryan.roberts@arm.com, r@hev.cc Cc: Andrew Morton , ajd@linux.ibm.com, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, brauner@kernel.org, catalin.marinas@arm.com, dev.jain@arm.com, jack@suse.cz, kees@kernel.org, kevin.brodsky@arm.com, lance.yang@linux.dev, Liam.Howlett@oracle.com, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, npache@redhat.com, rmclure@linux.ibm.com, Al Viro , will@kernel.org, willy@infradead.org, ziy@nvidia.com, hannes@cmpxchg.org, kas@kernel.org, shakeel.butt@linux.dev, kernel-team@meta.com References: <20260318105203.3288727-1-usama.arif@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260318105203.3288727-1-usama.arif@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B795D100005 X-Stat-Signature: mzk41giw7iqkzice5yhsapxb1cenorgq X-Rspam-User: X-HE-Tag: 1773906033-384459 X-HE-Meta: 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 vjfNKLd1 w/c8fB0k/SHbYmbQGVp0b0LrXUw3AlHOoyQvzza/bwPxDR3ov+RQEOIWt0xYCvuN63RwLfHDAoXZKL39MdYIb+E0k88pxRffBLk8h2mkS1RUwvBksmPVfjJ1+a1yfXELGniQmERG6Q64cpaRimbxBJjhUboKQqXGH8YWQI3X+/cVF1Mdn91Uw6G9uVhFQVa5VWbSGRMfhV/1K4ZRb3E1hWtljcC65RB9PrN/j0VARhjxOVrtVM2suzPDIxP8iNvhKWB9c6plF8OietJ5tVaZ0BC+2Rmk5OYPlOrjWedYaZfex+d24PvA5Km1jPWeBxM70jJe6 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/18/26 11:52, Usama Arif wrote: > On Fri, 13 Mar 2026 13:55:38 -0700 Usama Arif wrote: > >> On Fri, 13 Mar 2026 16:33:42 +0000 Ryan Roberts wrote: >> >>> >>> This was deliberate, although perhaps a bit conservative. I was concerned about >>> the possibility of read amplification; pointlessly reading in a load of memory >>> that never actually gets used. And that is independent of page size. >>> >>> 2M seems quite big as a default IMHO, I could imagine Android might complain >>> about memory pressure in their 16K config, for example. >>> >> >> The force_thp_readahead path in do_sync_mmap_readahead() reads at >> HPAGE_PMD_ORDER (2M on x86) and even doubles it to 4M for >> non VM_RAND_READ mappings (ra->size *= 2), with async readahead >> enabled. exec_folio_order() is more conservative. a single 2M folio >> with async_size=0, no speculative prefetch. So I think the memory >> pressure would not be worse than what x86 has? >> >> For memory pressure on Android 16K: the readahead is clamped to VMA >> boundaries, so a small shared library won't read 2M. >> page_cache_ra_order() reduces folio order near EOF and on allocation >> failure, so the 2M order is a preference, not a guarantee with the >> current code? >> > > I am not a big fan of introducing Kconfig options, but would > CONFIG_EXEC_FOLIO_ORDER with the default value being 64K be a better > solution? Or maybe a default of 64K for 4K and 16K base page size, > but 2M for 64K page size as 64K base page size is mostly for servers. > > Using a default value of 64K would mean no change in behaviour. I don't think such a tunable is the right approach. We should try to do something smarter in the kernel. We should have access to the mapping size and whether there is currently real memory pressure. We might even know the estimated speed of the device we're loading data from :) -- Cheers, David