Re: [LSF/MM/BPF TOPIC] Large block for I/O

Bart Van Assche
2024-01-08T19:30:13Z

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?

Thanks,

Bart.