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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, 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 BF528C43219 for ; Thu, 2 May 2019 18:17:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E69620B7C for ; Thu, 2 May 2019 18:17:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Aq6L7d8S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726145AbfEBSRB (ORCPT ); Thu, 2 May 2019 14:17:01 -0400 Received: from mail-wm1-f66.google.com ([209.85.128.66]:52289 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726120AbfEBSRA (ORCPT ); Thu, 2 May 2019 14:17:00 -0400 Received: by mail-wm1-f66.google.com with SMTP id j13so4182072wmh.2 for ; Thu, 02 May 2019 11:16:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=cWCo69133luBASwqa/1RXdxuYCSr1bgB2Hxe86cjhos=; b=Aq6L7d8SFUyNSZAfinh/FfJie0qFbBBoywO5dyD8SoCxAiLfkjLYgqWUIVKL7U/AaL dcci44SbmHhX7RhnIf/4OWTHDmlYGtDCHMpoCXhKGXwmD1EUmuirlL0zF2dcwdQafPd4 sO4ctLI9A03ucsNeGX7509pNymPvOcRnKSAGWFtiU2w0/yTrfMddmY3ByGu3a+BIyQb6 kzuhslUB952LdA8WQvwK7EzNQjLq6ynUQjVRArmQab3CuxJ4Ab8y6YgVJF9OtaAViq47 CD6/uxAncbyQlMEEQsbiOxGaE+o/iPhxIevNSK7BHtR2Rtd9EoFUdyZIwZC3lt9ZhYJb Lijw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=cWCo69133luBASwqa/1RXdxuYCSr1bgB2Hxe86cjhos=; b=WQtfuQ/mPsH1I2q/Id1DZ/vIvmqJE3koFN1WKcOSOnO6Zz4aQjLTjguq8XSLFXWt2X ys/xdsvUXeiITcIW0FLdRTg4fL2GGKmKETn4Z4sXsxitimayWdsQtrVMacsmoGZKmnRo mITbrgPhW1l4gkM/8UuyX9XACNUyXE2H9aniM284VqYgQnUZo6eB18XK/dTokzqHOWdY yMvfp2Sx9u0hgN5+G0IXJdfjY+GzplIJENUyDxtxcH5iA3kqYiJlsw/wxN/XotWjVr75 mDQsSYWEb7WqQAmOhpZC/YyAvIXhAIlBsOrMjzl9v+sNvxa1ms2KIlBN0BCPFb+JhN7t +yYA== X-Gm-Message-State: APjAAAXZJ3lOuRinw1EzmRYhCDHnARCxCMF35EAMsd6jsx1s8tTy32O/ bfeLEnqh5Hzkofa/wqltxX9RxDPYZZT6lCFe5KU= X-Google-Smtp-Source: APXvYqzmZlpa5BteU8S97PXVz1pRkY4PIA06hfNR91/FlHSyhmZKnpiRu2VHkotzhBpZ3Z+UQfvljhROAIeq72Govss= X-Received: by 2002:a7b:cd18:: with SMTP id f24mr3260045wmj.19.1556821019080; Thu, 02 May 2019 11:16:59 -0700 (PDT) MIME-Version: 1.0 References: <20190502040331.81196-1-ezemtsov@google.com> In-Reply-To: From: Richard Weinberger Date: Thu, 2 May 2019 20:16:48 +0200 Message-ID: Subject: Re: Initial patches for Incremental FS To: Amir Goldstein Cc: ezemtsov@google.com, linux-fsdevel , Theodore Tso , Miklos Szeredi Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, May 2, 2019 at 1:21 PM Amir Goldstein wrote: > > On Thu, May 2, 2019 at 12:04 AM wrote: > > > > Hi All, > > > > Please take a look at Incremental FS. > > > > Incremental FS is special-purpose Linux virtual file system that allows > > execution of a program while its binary and resource files are still be= ing > > lazily downloaded over the network, USB etc. It is focused on increment= al > > delivery for a small number (under 100) of big files (more than 10 mega= bytes each). > > Incremental FS doesn=E2=80=99t allow direct writes into files and, once= loaded, file > > content never changes. Incremental FS doesn=E2=80=99t use a block devic= e, instead it > > saves data into a backing file located on a regular file-system. > > > > What=E2=80=99s it for? > > > > It allows running big Android apps before their binaries and resources = are > > fully loaded to an Android device. If an app reads something not loaded= yet, > > it needs to wait for the data block to be fetched, but in most cases ho= t blocks > > can be loaded in advance and apps can run smoothly and almost instantly= . > > This sounds very useful. > > Why does it have to be a new special-purpose Linux virtual file? > Why not FUSE, which is meant for this purpose? > Those are things that you should explain when you are proposing a new > filesystem, > but I will answer for you - because FUSE page fault will incur high > latency also after > blocks are locally available in your backend store. Right? > > How about fscache support for FUSE then? > You can even write your own fscache backend if the existing ones don't > fit your needs for some reason. > > Do you know of the project https://vfsforgit.org/? > Not exactly the same use case but very similar. > There is ongoing work on a Linux port developed by GitHub.com: > https://github.com/github/libprojfs > > Piling logic into the kernel is not the answer. > Adding the missing interfaces to the kernel is the answer. I wonder whether userfaultfd can but used for that use-case too? --=20 Thanks, //richard