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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 766BDC47420 for ; Thu, 24 Sep 2020 17:20:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2955F2395C for ; Thu, 24 Sep 2020 17:20:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="qNlQD2VU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728613AbgIXRT4 (ORCPT ); Thu, 24 Sep 2020 13:19:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727216AbgIXRT4 (ORCPT ); Thu, 24 Sep 2020 13:19:56 -0400 Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E3EBC0613CE; Thu, 24 Sep 2020 10:19:56 -0700 (PDT) Received: by mail-wr1-x442.google.com with SMTP id s12so4661299wrw.11; Thu, 24 Sep 2020 10:19:56 -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; bh=kAbZd3vS2mRaNP4IzKbD5ITPH51zcyuJzcimZuIDrHU=; b=qNlQD2VUwuZlfp3QTbChXLwkrg3TPs4FW/cPGjFxkYsyIdgolpsVHCzK+JtmhzuOVy pdi0dktqgCnXlIOv5hDbMPTnXdMBVdkZQoe7O2BW6Bbczk9+1s2DIwD9PrSuK6v+sEaF DI5dYuyUqGJB5Cqg0RJ5MGE9wp6SI2DQKTHm83cS8wjNJQ+D8i9i22W5Wc0KAEJPt/lI lMqIAU3dAoFQknurRyITwbWpD/XwQwQH7f+RMIfkHbp/eYOroyMTFqQ42nmLRTZ0AFEs ZImi//w1eD9Vr/kJD930rSvZA6+0qyZXWvUYBdxkM9YPx/4j22h5EaLNGpyTSrXMbCwO YKUA== 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; bh=kAbZd3vS2mRaNP4IzKbD5ITPH51zcyuJzcimZuIDrHU=; b=V21uYvRbHZmmTSh3fWjo8BfbaL41yrIXH/LzNGG90j0d+TEjVPxei13O3cZ/CpZi+w dsQ5Rxqv8mfkZ3D/pKzhGpeonQs2ixAtmuCBguC+xWnAICRlXSDVEll/jQrmPgCJYruh KllSIWPU7j23jrqZi4AFt2/qZBce5bWkFU9a3e9ODDq1/ml3Fk0EI1QgXibidClGM8OI ncDnarO0V5INSytdvFJnjZ4G59CJnm48s5WRI3gvbqYIF7dbkiI5xB80SlFjVubtCGSU P9GYtyPCCG2iA5FhX7sSPkgXvlcTSlbcqbHQoXP3lT1DLMkkOzOkXMFH0cm0Akxu2jQv TrMw== X-Gm-Message-State: AOAM530qgixWz+BMK83Ty3+x2kopAJJW9TEPB6zrRV56pBTp1V6WUU8e VJqic41txBqV6JiPJvkwadNM0DDkiCM0YaRmwXf1XTevHy6UDYEwhJE= X-Google-Smtp-Source: ABdhPJxhIbv58SUHooN6WEjrkYW8U18ujKGcxnMYrWPH1bVWcmnQmjph4Yyi6hSpgSDoFyjg4oEh0yHOb+QZtev8xNw= X-Received: by 2002:adf:dd51:: with SMTP id u17mr834011wrm.355.1600967994708; Thu, 24 Sep 2020 10:19:54 -0700 (PDT) MIME-Version: 1.0 References: <20200731091416.GA29634@infradead.org> <20200731094135.GA4104@infradead.org> <20200731125110.GA11500@infradead.org> <20200814081411.GA16943@infradead.org> <20200908151801.GA16742@infradead.org> In-Reply-To: <20200908151801.GA16742@infradead.org> From: Kanchan Joshi Date: Thu, 24 Sep 2020 22:49:28 +0530 Message-ID: Subject: Re: [PATCH v4 6/6] io_uring: add support for zone-append To: "hch@infradead.org" Cc: Damien Le Moal , Jens Axboe , Pavel Begunkov , Kanchan Joshi , "viro@zeniv.linux.org.uk" , "bcrl@kvack.org" , Matthew Wilcox , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-aio@kvack.org" , "io-uring@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-api@vger.kernel.org" , SelvaKumar S , Nitesh Shetty , Javier Gonzalez , Johannes Thumshirn , Naohiro Aota Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Sep 8, 2020 at 8:48 PM hch@infradead.org wrote: > > On Mon, Sep 07, 2020 at 12:31:42PM +0530, Kanchan Joshi wrote: > > But there are use-cases which benefit from supporting zone-append on > > raw block-dev path. > > Certain user-space log-structured/cow FS/DB will use the device that > > way. Aerospike is one example. > > Pass-through is synchronous, and we lose the ability to use io-uring. > > So use zonefs, which is designed exactly for that use case. Not specific to zone-append, but in general it may not be good to lock new features/interfaces to ZoneFS alone, given that direct-block interface has its own merits. Mapping one file to a one zone is good for some use-cases, but limiting for others. Some user-space FS/DBs would be more efficient (less meta, indirection) with the freedom to decide file-to-zone mapping/placement. - Rocksdb and those LSM style DBs would map SSTable to zone, but SSTable file may be two small (initially) and may become too large (after compaction) for a zone. - The internal parallelism of a single zone is a design-choice, and depends on the drive. Writing multiple zones parallely (striped/raid way) can give better performance than writing on one. In that case one would want to file that seamlessly combines multiple-zones in a striped fashion. Also it seems difficult (compared to block dev) to fit simple-copy TP in ZoneFS. The new command needs: one NVMe drive, list of source LBAs and one destination LBA. In ZoneFS, we would deal with N+1 file-descriptors (N source zone file, and one destination zone file) for that. While with block interface, we do not need more than one file-descriptor representing the entire device. With more zone-files, we face open/close overhead too. -- Joshi