Re: [RFC PATCH v2 0/2] introduce io_uring_cmd_import_fixed_vec

[Pavel Begunkov]

On 3/13/25 13:15, Pavel Begunkov wrote:
> On 3/13/25 10:44, Sidong Yang wrote:
> > On Thu, Mar 13, 2025 at 08:57:45AM +0000, Pavel Begunkov wrote:
> > > On 3/12/25 14:23, Sidong Yang wrote:
> > > > This patche series introduce io_uring_cmd_import_vec. With this function,
> > > > Multiple fixed buffer could be used in uring cmd. It's vectored version
> > > > for io_uring_cmd_import_fixed(). Also this patch series includes a usage
> > > > for new api for encoded read in btrfs by using uring cmd.
> > >
> > > Pretty much same thing, we're still left with 2 allocations in the
> > > hot path. What I think we can do here is to add caching on the
> > > io_uring side as we do with rw / net, but that would be invisible
> > > for cmd drivers. And that cache can be reused for normal iovec imports.
> > >
> > > https://github.com/isilence/linux.git regvec-import-cmd
> > > (link for convenience)
> > > https://github.com/isilence/linux/tree/regvec-import-cmd
> > >
> > > Not really target tested, no btrfs, not any other user, just an idea.
> > > There are 4 patches, but the top 3 are of interest.
> >
> > Thanks, I justed checked the commits now. I think cache is good to resolve
> > this without allocation if cache hit. Let me reimpl this idea and test it
> > for btrfs.
>
> Sure, you can just base on top of that branch, hashes might be
> different but it's identical to the base it should be on. Your
> v2 didn't have some more recent merged patches.

Jens' for-6.15/io_uring-reg-vec specifically, but for-next likely
has it merged.

--
Pavel Begunkov