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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E2BFC6FD19 for ; Mon, 6 Mar 2023 10:05:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229914AbjCFKF0 (ORCPT ); Mon, 6 Mar 2023 05:05:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229980AbjCFKFZ (ORCPT ); Mon, 6 Mar 2023 05:05:25 -0500 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8FBF712F1A; Mon, 6 Mar 2023 02:05:22 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 303971FDDD; Mon, 6 Mar 2023 10:05:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1678097121; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QRb9m2gaQoCLctLOiYS3tE6uGi3yOZ0FLkQqw+fFybA=; b=TCnLqFQlPrObIJ2juVIYjrKmRoTrx3k99z6KhVWYekZPPw4ynNrbxuEsuJyGzff3GXyFrc CT1C3eappXnvVCbJf0hQ0fzjmVpnF9YlkcQBlsqQDlNpTvb3caMPsk4txIfgvmN4gv/vN/ 0r9LGeBBDqu5g9VOWeI5mjwMNpGveMw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1678097121; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QRb9m2gaQoCLctLOiYS3tE6uGi3yOZ0FLkQqw+fFybA=; b=7QsEJHCXVvi7r+XMVVSbIhVXqO5yz9jL2VMCXu13ylzuQLIZRnMx4a1gUJcfr6lVtP1Xi1 dvhhF7CN5Z15hZBw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 17ACE13A66; Mon, 6 Mar 2023 10:05:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id BJXfBOG6BWSXbwAAMHmgww (envelope-from ); Mon, 06 Mar 2023 10:05:21 +0000 Message-ID: Date: Mon, 6 Mar 2023 11:05:20 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [LSF/MM/BPF TOPIC] Cloud storage optimizations To: Matthew Wilcox Cc: Luis Chamberlain , Keith Busch , Theodore Ts'o , Pankaj Raghav , Daniel Gomez , =?UTF-8?Q?Javier_Gonz=c3=a1lez?= , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org References: <0b70deae-9fc7-ca33-5737-85d7532b3d33@suse.de> Content-Language: en-US From: Hannes Reinecke In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 3/6/23 09:23, Matthew Wilcox wrote: > On Sun, Mar 05, 2023 at 12:22:15PM +0100, Hannes Reinecke wrote: >> On 3/4/23 18:54, Matthew Wilcox wrote: >>> I think we're talking about different things (probably different storage >>> vendors want different things, or even different people at the same >>> storage vendor want different things). >>> >>> Luis and I are talking about larger LBA sizes. That is, the minimum >>> read/write size from the block device is 16kB or 64kB or whatever. >>> In this scenario, the minimum amount of space occupied by a file goes >>> up from 512 bytes or 4kB to 64kB. That's doable, even if somewhat >>> suboptimal. >>> >> And so do I. One can view zones as really large LBAs. >> >> Indeed it might be suboptimal from the OS point of view. >> But from the device point of view it won't. >> And, in fact, with devices becoming faster and faster the question is >> whether sticking with relatively small sectors won't become a limiting >> factor eventually. >> >>> Your concern seems to be more around shingled devices (or their equivalent >>> in SSD terms) where there are large zones which are append-only, but >>> you can still random-read 512 byte LBAs. I think there are different >>> solutions to these problems, and people are working on both of these >>> problems. >>> >> My point being that zones are just there because the I/O stack can only deal >> with sectors up to 4k. If the I/O stack would be capable of dealing >> with larger LBAs one could identify a zone with an LBA, and the entire issue >> of append-only and sequential writes would be moot. >> Even the entire concept of zones becomes irrelevant as the OS would >> trivially only write entire zones. > > All current filesystems that I'm aware of require their fs block size > to be >= LBA size. That is, you can't take a 512-byte blocksize ext2 > filesystem and put it on a 4kB LBA storage device. > > That means that files can only grow/shrink in 256MB increments. I > don't think that amount of wasted space is going to be acceptable. > So if we're serious about going down this path, we need to tell > filesystem people to start working out how to support fs block > size < LBA size. > > That's a big ask, so let's be sure storage vendors actually want > this. Both supporting zoned devices & suporting 16k/64k block > sizes are easier asks. Why, I know. And this really is a future goal. (Possibly a very _distant_ future goal.) Indeed we should concentrate on getting 16k/64k blocks initially. Or maybe 128k blocks to help our RAIDed friends. Cheers, Hannes