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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32EA0C43387 for ; Thu, 17 Jan 2019 21:17:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3C1920855 for ; Thu, 17 Jan 2019 21:17:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Sa26W7bH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728658AbfAQVRJ (ORCPT ); Thu, 17 Jan 2019 16:17:09 -0500 Received: from mail-it1-f196.google.com ([209.85.166.196]:50569 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728286AbfAQVRJ (ORCPT ); Thu, 17 Jan 2019 16:17:09 -0500 Received: by mail-it1-f196.google.com with SMTP id z7so3756675iti.0 for ; Thu, 17 Jan 2019 13:17:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=pw+v7EhjpTqDPHVtrl88tsrhCZ87xWX/hhIqge9wmy4=; b=Sa26W7bHL05zpDg9ApLsxgHRMK6Nnb/0iqDWEwvf+NlmL+QJn3SGhZm9qeiLF+gLn8 YkiUJX4QiXr0OnpNkfRUC9OwCNd0xdAZcalUIprAs+nOU7zWADXJUi2nbhrr+IxUXo4c DnhEHyJ9hYEn2lMZZz/BStla7Hmg3dYzQx8NStcfr+t7CVkTimDwj7g1IMuGCYOga5WJ yHhO1yhVUV1FFpDr2PQbj3378lYq9XAoSk6Epvw/FH+pU0ydq22GmeFZXGqGa5rUayTa FbqYovHhDzNa6s+zSn02kSSZEsQxQVAXid/D1GKiTIVWHkeF+HD8TowBZg3EiyDUNg4n ws+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=pw+v7EhjpTqDPHVtrl88tsrhCZ87xWX/hhIqge9wmy4=; b=oOF2YjG/17rwQRk1g3SXdmwwJfJ0vNGKho3u4N0iEg+lTY1kLVchCztHIU3YkVuSFx JT6R2aLnR2XVe8GAmWGZXSCLfh/J/2fw6UaZ7LWG4J7/y+YHA2TYRxqydwga48MyXvkI UTxy2ti1QGE1XfIr49l3wBYvj1JkvTWlUI5pCEKCOoTbba/IWHRTp/fD+rsBgEj5h0Mx hdF3sEe3V1hjLlfzdeWP9Uy56CL5cOPhh3PKMqca2gD80deUAYQrSbG/YrjuM2cdScjR 1aq7QC/SBcXI0GCXkmWws9HwL25RBVdkuF5ebwnfyWUGfEVNruMYIV+JBl4+Fly6e3ic x8XQ== X-Gm-Message-State: AJcUukej34tCwAfR/RS/Mv3ZRVCmi1P5XIImg13aa8n3ePzQBrSMezyl NH9hQmf1ZBccS09yGC9QTPjW7sxcycte3g== X-Google-Smtp-Source: ALg8bN7liKCAGbkrD5qNGSm/OcNBj7fVwYBBCyw9tnmKwS88Sa6ezYN0WOxiBleLQiAWWwTJhpxE+w== X-Received: by 2002:a24:70d2:: with SMTP id f201mr9208483itc.127.1547759828255; Thu, 17 Jan 2019 13:17:08 -0800 (PST) Received: from [192.168.1.56] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id k64sm1249449itb.7.2019.01.17.13.17.06 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Jan 2019 13:17:07 -0800 (PST) Subject: Re: [PATCH 05/15] Add io_uring IO interface To: Jeff Moyer Cc: Roman Penyaev , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, avi@scylladb.com, linux-block-owner@vger.kernel.org References: <20190116175003.17880-1-axboe@kernel.dk> <20190116175003.17880-6-axboe@kernel.dk> <718b4d1fbe9f97592d6d7b76d7a4537d@suse.de> <02568485-cd10-182d-98e3-619077cf9bdc@kernel.dk> <3180aa85-68a6-0eb2-082b-f177344cefa9@kernel.dk> From: Jens Axboe Message-ID: Date: Thu, 17 Jan 2019 14:17:05 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 1/17/19 2:02 PM, Jeff Moyer wrote: > Jens Axboe writes: > >>>>>>>> It seems that sq_entries, cq_entries are not limited at all. Can nasty >>>>>>>> app consume a lot of kernel pages calling io_setup_uring() from a loop >>>>>>>> passing random entries number? (or even better: decreasing entries >>>>>>>> number, >>>>>>>> in order to consume all pages orders with min number of loops). > ... >>>> One concern here is that, at least looking at my boxes, the default >>>> setting for RLIMIT_MEMLOCK is really low. I'd hate for everyone to run >>>> into issues using io_uring just because it seems to require root, >>>> because the memlock limit is so low. >>>> >>>> That's much less of a concern with the fixed buffers, since it's a more >>>> esoteric part of it. But everyone should be able to setup a few io_uring >>>> queues and use them without having to worry about failing due to an >>>> absurdly low RLIMIT_MEMLOCK. >>>> >>>> Comments? >>> >>> Yeah, the default is 64k here. We should probably up that. I'd say we >>> either tackle the ridiculously low rlimits, or I guess we just go the >>> aio route and add a sysctl. :-\ I'll see what's involved in the >>> former. >> >> After giving it a bit of thought, let's go the rlimit route. It is cleaner, >> and I don't want a sysctl knob for this either. 64k will enable anyone to >> set up at least one decently sized ring. > > OK. Note that the MLOCK_LIMIT size has been dictated by gpg's > requirements: > > commit f947ff8af30f75cb9cf0e966caf8f4809ad1b92e > Author: Rik van Riel > Date: Sun Aug 22 23:06:58 2004 -0700 > > [PATCH] increase per-user mlock limit default to 32k > > Since various gnupg users have indicated that gpg wants to mlock 32kB of > memory, I created the patch below that increases the default mlock ulimit > to 32kB. > > and then > > commit 0833422274ff00729a603b020fac297e69a03e40 > Author: Kurt Garloff > Date: Wed Oct 29 14:00:48 2008 -0700 > > mm: increase the default mlock limit from 32k to 64k > > ... > However, newer gpg2 needs 64k in various circumstances and otherwise > fails miserably, see bnc#329675. > > So all we need to do is modify gpg2 so that is requires more locked > memory, and we're golden! ;-) Haha, that's some nice digging there! Yes, we could bump it, but with the default, we can get a 512 sized ring per user, that's 13 pages (rounded up). Probably good enough to get things off the ground? -- Jens Axboe