From: Matthew Wilcox <willy@infradead.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Hannes Reinecke <hare@suse.de>,
lsf-pc@lists.linuxfoundation.org, linux-mm@kvack.org,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: [LSF/MM/BPF TOPIC] Large block for I/O
Date: Mon, 8 Jan 2024 19:35:17 +0000 [thread overview]
Message-ID: <ZZxOdWoHrKH4ImL7@casper.infradead.org> (raw)
In-Reply-To: <9b46c48f-d7c4-4ed3-a644-fba90850eab8@acm.org>
On Mon, Jan 08, 2024 at 11:30:10AM -0800, Bart Van Assche wrote:
> On 12/21/23 21:37, Christoph Hellwig wrote:
> > On Fri, Dec 22, 2023 at 05:13:43AM +0000, Matthew Wilcox wrote:
> > > It clearly solves a problem (and the one I think it's solving is the
> > > size of the FTL map). But I can't see why we should stop working on it,
> > > just because not all drive manufacturers want to support it.
> >
> > I don't think it is drive vendors. It is is the SSD divisions which
> > all pretty much love it (for certain use cases) vs the UFS/eMMC
> > divisions which tends to often be fearful and less knowledgeable (to
> > say it nicely) no matter what vendor you're talking to.
>
> Hi Christoph,
>
> If there is a significant number of 4 KiB writes in a workload (e.g.
> filesystem metadata writes), and the logical block size is increased from
> 4 KiB to 16 KiB, this will increase write amplification no matter how the
> SSD storage controller has been designed, isn't it? Is there perhaps
> something that I'm misunderstanding?
You're misunderstanding that it's the _drive_ which gets to decide the
logical block size. Filesystems literally can't do 4kB writes to these
drives; you can't do a write smaller than a block. If your clients
don't think it's a good tradeoff for them, they won't tell Linux that
the minimum IO size is 16kB.
Some workloads are better with a 4kB block size, no doubt. Others are
better with a 512 byte block size. That doesn't prevent vendors from
offering 4kB LBA size drives.
next prev parent reply other threads:[~2024-01-08 19:35 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <7970ad75-ca6a-34b9-43ea-c6f67fe6eae6@iogearbox.net>
2023-12-20 10:01 ` LSF/MM/BPF: 2024: Call for Proposals Daniel Borkmann
2023-12-20 15:03 ` [LSF/MM/BPF TOPIC] Large block for I/O Hannes Reinecke
2023-12-21 20:33 ` Bart Van Assche
2023-12-21 20:42 ` Matthew Wilcox
2023-12-21 21:00 ` Bart Van Assche
2023-12-22 5:09 ` Christoph Hellwig
2023-12-22 5:13 ` Matthew Wilcox
2023-12-22 5:37 ` Christoph Hellwig
2024-01-08 19:30 ` Bart Van Assche
2024-01-08 19:35 ` Matthew Wilcox [this message]
2024-02-22 18:45 ` Luis Chamberlain
2024-02-25 23:09 ` Dave Chinner
2024-02-26 15:25 ` Luis Chamberlain
2024-03-07 1:59 ` Luis Chamberlain
2024-03-07 5:31 ` Dave Chinner
2024-03-07 7:29 ` Luis Chamberlain
2023-12-22 8:23 ` Viacheslav Dubeyko
2023-12-22 12:29 ` Hannes Reinecke
2023-12-22 13:29 ` Matthew Wilcox
2023-12-22 15:10 ` Keith Busch
2023-12-22 16:06 ` Matthew Wilcox
2023-12-25 8:55 ` Viacheslav Dubeyko
2023-12-25 8:12 ` Viacheslav Dubeyko
2024-02-23 16:41 ` Pankaj Raghav (Samsung)
2024-01-17 13:37 ` LSF/MM/BPF: 2024: Call for Proposals [Reminder] Daniel Borkmann
2024-02-14 13:03 ` LSF/MM/BPF: 2024: Call for Proposals [Final Reminder] Daniel Borkmann
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