SQE OP - sendfile

SQE OP - sendfile

[Mark Papadakis]

Greetings,

Are there any plans for an SENDFILE SQE OP?
Using a pipe and 2 two SPLICE ops(using the LINK flag) for moving data from one file FD to a socket FD(for example) works - but it’s somewhat inconvenient and maybe more expensive than it would otherwise be if there was a dedicated op for a sendfile() like facility.

Thank you,
@markpapadakis

Re: SQE OP - sendfile

[Pavel Begunkov]

On 29/04/2020 18:21, Mark Papadakis wrote:
> Greetings,
> 
> Are there any plans for an SENDFILE SQE OP?
> Using a pipe and 2 two SPLICE ops(using the LINK flag) for moving data from one file FD to a socket FD(for example) works - but it’s somewhat inconvenient and maybe more expensive than it would otherwise be if there was a dedicated op for a sendfile() like facility.
> 

I didn't dig deeply, but it's done by internally creating a pipe and leaving it
with a task up until it exits. I hope such pipes use only 1 page or so, but I
don't like the idea of having one per each io-wq thread (even lazily as it's
done now).

If we really want to do that, would probably need something more elaborate.
Jens may shed some light.

-- 
Pavel Begunkov