Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753134AbdHJRg4 (ORCPT ); Thu, 10 Aug 2017 13:36:56 -0400 Received: from mail-pg0-f65.google.com ([74.125.83.65]:35185 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752629AbdHJRgx (ORCPT ); Thu, 10 Aug 2017 13:36:53 -0400 Date: Thu, 10 Aug 2017 10:36:51 -0700 From: Eric Biggers To: "Austin S. Hemmelgarn" Cc: Nick Terrell , Herbert Xu , kernel-team@fb.com, squashfs-devel@lists.sourceforge.net, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: Re: [PATCH v5 2/5] lib: Add zstd modules Message-ID: <20170810173651.GB90916@gmail.com> References: <20170810023553.3200875-1-terrelln@fb.com> <20170810023553.3200875-3-terrelln@fb.com> <20170810083017.GA10462@zzz.localdomain> <671b5ffb-0a8b-4e70-e3ac-9754cea54829@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <671b5ffb-0a8b-4e70-e3ac-9754cea54829@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 833 Lines: 16 On Thu, Aug 10, 2017 at 10:57:01AM -0400, Austin S. Hemmelgarn wrote: > Also didn't think to mention this, but I could see the max level > being very popular for use with SquashFS root filesystems used in > LiveCD's. Currently, they have to decide between read performance > and image size, while zstd would provide both. The high compression levels of Zstandard are indeed a great fit for SquashFS, but SquashFS images are created in userspace by squashfs-tools. The kernel only needs to be able to decompress them. (Also, while Zstandard provides very good tradeoffs and will probably become the preferred algorithm for SquashFS, it's misleading to imply that users won't have to make decisions anymore. It does not compress as well as XZ or decompress as fast as LZ4, except maybe in very carefully crafted benchmarks.) Eric