Re: [PATCH v7 0/3] FDP and per-io hints

Christoph Hellwig
2024-10-11T08:59:10Z

On Thu, Oct 10, 2024 at 02:27:33PM +0200, Javier Gonzalez wrote:

[full quote snipped, it would be really helpful to only quote what you
actuall reference per the usual email rules]

>> Data placement by-file is based on that the lifetime of a file's data
>> blocks are strongly correlated. When a file is deleted, all its blocks
>> will be reclaimable at that point. This requires knowledge about the
>> data placement buckets and works really well without any hints
>> provided.
>
> But we need hints to put files together. I believe you do this already,
> as no placement protocol gives you unlimited separation.

The per-file temperature hints do a reasonable job for that. A fully
developed version of the separate write streams submitted by Kanchan
would probably do even better, but for now the per-file hints seem
to be enough.

> Maybe you can post some patches on the parts dedicated to the VFS level
> and user-space API (syscall or uring)?

It's just using the existing temperature hints.