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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AE2DC433EF for ; Tue, 16 Nov 2021 20:06:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3A41361BAA for ; Tue, 16 Nov 2021 20:06:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3A41361BAA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=pengaru.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id F2CE56B0081; Tue, 16 Nov 2021 15:05:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E45066B0085; Tue, 16 Nov 2021 15:05:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B0B3E6B0082; Tue, 16 Nov 2021 15:05:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0081.hostedemail.com [216.40.44.81]) by kanga.kvack.org (Postfix) with ESMTP id 95C526B0081 for ; Tue, 16 Nov 2021 15:05:44 -0500 (EST) Received: from forelay.prod.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by fograve02.hostedemail.com (Postfix) with ESMTP id 50921852E1 for ; Tue, 16 Nov 2021 19:46:56 +0000 (UTC) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1B50985D6D for ; Tue, 16 Nov 2021 19:46:46 +0000 (UTC) X-FDA: 78815826012.16.51E81AC Received: from shells.gnugeneration.com (shells.gnugeneration.com [66.240.222.126]) by imf12.hostedemail.com (Postfix) with ESMTP id 73C9910000AF for ; Tue, 16 Nov 2021 19:46:45 +0000 (UTC) Received: by shells.gnugeneration.com (Postfix, from userid 1000) id AF72A1A40175; Tue, 16 Nov 2021 11:46:44 -0800 (PST) Date: Tue, 16 Nov 2021 11:46:44 -0800 From: Vito Caputo To: Drew DeVault Cc: Jens Axboe , Matthew Wilcox , Andrew Morton , Ammar Faizi , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, io_uring Mailing List , Pavel Begunkov , linux-mm@kvack.org Subject: Re: [PATCH] Increase default MLOCK_LIMIT to 8 MiB Message-ID: <20211116194644.uyvfz4zzzjlbfqbm@shells.gnugeneration.com> References: <20211028080813.15966-1-sir@cmpwn.com> <593aea3b-e4a4-65ce-0eda-cb3885ff81cd@gnuweeb.org> <20211115203530.62ff33fdae14927b48ef6e5f@linux-foundation.org> <20211116192148.vjdlng7pesbgjs6b@shells.gnugeneration.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: y8q4rf8t6qqjwa19em67n6ezh3otozma Authentication-Results: imf12.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf12.hostedemail.com: domain of swivel@shells.gnugeneration.com designates 66.240.222.126 as permitted sender) smtp.mailfrom=swivel@shells.gnugeneration.com X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 73C9910000AF X-HE-Tag: 1637092005-610753 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Nov 16, 2021 at 08:25:33PM +0100, Drew DeVault wrote: > On Tue Nov 16, 2021 at 8:21 PM CET, Vito Caputo wrote: > > Considering a single fullscreen 32bpp 4K-resolution framebuffer is > > ~32MiB, I'm not convinced this is really correct in nearly 2022. > > Can you name a practical use-case where you'll be doing I/O with > uncompressed 4K framebuffers? The kind of I/O which is supported by > io_uring, to be specific, not, say, handing it off to libdrm. Obviously video/image editing software tends to operate on raw frames, and sometimes even persists them via filesystems. I haven't given it a lot of thought, but a framebuffer is a commonly used unit of memory allocation in code run on the CPU I've written over the years. Being able to pin those for something like io_uring (or some other DMA-possible interface) seems like an obvious memory-hungry thing to consider here if we're talking default upper bounds. Regards, Vito Caputo