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Sat, 4 Mar 2023 11:08:37 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id P+QzLLUmA2SaTQAAMHmgww (envelope-from ); Sat, 04 Mar 2023 11:08:37 +0000 Message-ID: Date: Sat, 4 Mar 2023 12:08:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [LSF/MM/BPF TOPIC] Cloud storage optimizations Content-Language: en-US To: Luis Chamberlain , Matthew Wilcox Cc: 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: From: Hannes Reinecke In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8D5F01C0010 X-Stat-Signature: zoaxmnh6bo8mpjt43yqtjur3d5bb4fzo X-HE-Tag: 1677928119-586165 X-HE-Meta: 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 YeuVSYEg dKjR1XFiKv2f+6WRQnIQi7vR/drTxS8fTVUKonZRk3Lm/yWL+0W4y1TQ9KQpEPOomvwKWosd3tj0H6H7pS23ZHiBh9ErlKyueEWCC+5q/IiwMFA7wcDBMIcFf5O/Jm9z6dh3X2UcV81hkRgizvohiFUXexRCloLd0QYfFD3Paquc7PQ9WEAuhwmRtVx7cdM+QJ6hMtOYeWfsizy9oll9vss41pkcTRAc2V1NLy/argMJYs9AVFPWIoHQXZX2JJEZBnpVsJ6RDQDr9RPaxvmjvMmzAfdEeuSkWfFenPjoHwkpwlzA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/3/23 22:45, Luis Chamberlain wrote: > On Fri, Mar 03, 2023 at 03:49:29AM +0000, Matthew Wilcox wrote: >> On Thu, Mar 02, 2023 at 06:58:58PM -0700, Keith Busch wrote: >>> That said, I was hoping you were going to suggest supporting 16k logical block >>> sizes. Not a problem on some arch's, but still problematic when PAGE_SIZE is >>> 4k. :) >> >> I was hoping Luis was going to propose a session on LBA size > PAGE_SIZE. >> Funnily, while the pressure is coming from the storage vendors, I don't >> think there's any work to be done in the storage layers. It's purely >> a FS+MM problem. > > You'd hope most of it is left to FS + MM, but I'm not yet sure that's > quite it yet. Initial experimentation shows just enabling > PAGE_SIZE > physical & logical block NVMe devices gets brought down to 512 bytes. > That seems odd to say the least. Would changing this be an issue now? > > I'm gathering there is generic interest in this topic though. So one > thing we *could* do is perhaps review lay-of-the-land of interest and > break down what we all think are things likely could be done / needed. > At the very least we can come out together knowing the unknowns together. > > I started to think about some of these things a while ago and with the > help of Willy I tried to break down some of the items I gathered from him > into community OKRs (super informal itemization of goals and sub tasks which > would complete such goals) and started trying to take a stab at them > with our team, but obviously I think it would be great if we all just > divide & and conquer here. So maybe reviewing these and extending them > as a community would be good: > > https://kernelnewbies.org/KernelProjects/large-block-size > > I'm recently interested in tmpfs so will be taking a stab at higher > order page size support there to see what blows up. > Cool. > The other stuff like general IOMAP conversion is pretty well known, and > we already I think have a proposed session on that. But there is also > even smaller fish to fry, like *just* doing a baseline with some > filesystems with 4 KiB block size seems in order. > > Hearing filesystem developer's thoughts on support for larger block > size in light of lower order PAGE_SIZE would be good, given one of the > odd situations some distributions / teams find themselves in is trying > to support larger block sizes but with difficult access to higher > PAGE_SIZE systems. Are there ways to simplify this / help us in general? > Without it's a bit hard to muck around with some of this in terms of > support long term. This also got me thinking about ways to try to replicate > larger IO virtual devices a bit better too. While paying a cloud > provider to test this is one nice option, it'd be great if I can just do > this in house with some hacks too. For virtio-blk-pci at least, for instance, > I wondered whether using just the host page cache suffices, or would a 4K > page cache on the host modify say a 16 k emualated io controller results > significantly? How do we most effectively virtualize 16k controllers > in-house? > > To help with experimenting with large io and NVMe / virtio-blk-pci I > recented added support to intantiate tons of large IO devices to kdevops > [0], with it it should be easy to reproduce odd issues we may come up > with. For instnace it should be possible to subsequently extend the > kdevops fstests or blktests automation support with just a few Kconfig files > to use some of these largio devices to see what blows up. > We could implement a (virtual) zoned device, and expose each zone as a block. That gives us the required large block characteristics, and with a bit of luck we might be able to dial up to really large block sizes like the 256M sizes on current SMR drives. ublk might be a good starting point. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew Myers, Andrew McDonald, Martje Boudien Moerman