Re: [EXT] Re: [PATCHv11 0/9] write hints with nvme fdp and scsi streams

Christoph Hellwig
2024-11-15T16:53:59Z

On Fri, Nov 15, 2024 at 09:28:05AM -0700, Keith Busch wrote:
> SSDs operates that way. FDP just reports more stuff because that's what
> people kept asking for. But it doesn't require you fundamentally change
> how you acces it. You've singled out FDP to force a sequential write
> requirement that that requires unique support from every filesystem
> despite the feature not needing that.

No I haven't. If you think so you are fundamentally misunderstanding
what I'm saying.

> We have demonstrated 40% reduction in write amplifcation from doing the
> most simplist possible thing that doesn't require any filesystem or
> kernel-user ABI changes at all. You might think that's not significant
> enough to let people realize those gains without more invasive block
> stack changes, but you may not buying NAND in bulk if that's the case.

And as iterared multiple times you are doing that by bypassing the
file system layer in a forceful way that breaks all abstractions and
makes your feature unavailabe for file systems.

I've also thrown your a nugget by first explaining and then even writing
protype code to show how you get what you want while using the proper
abstractions. But instead of a picking up on that you just whine like
this. Either spend a little bit of effort to actually get the interface
right or just shut up.