Re: [PATCH RFC 7/9] io_uring: Introduce IORING_OP_CLONE

[Pavel Begunkov <asml.silence@gmail.com>]

On 12/11/24 17:26, Josh Triplett wrote:
> On Wed, Dec 11, 2024 at 01:37:40PM +0000, Pavel Begunkov wrote:
>> Also, do you block somewhere all other opcodes? If it's indeed
>> an under initialised task then it's not safe to run most of them,
>> and you'd never know in what way, unfortunately. An fs write
>> might need a net namespace, a send/recv might decide to touch
>> fs_struct and so on.
> 
> I would not expect the new task to be under-initialised, beyond the fact
> that it doesn't have a userspace yet (e.g. it can't return to userspace

I see, that's good. What it takes to setup a userspace? and is
it expensive? I remember there were good numbers at the time and
I'm to see where the performance improvement comes from. Is it
because the page table is shared? In other word what's the
difference comparing to spinning a new (user space) thread and
executing the rest with a new io_uring instance from it?


> without exec-ing first); if it is, that'd be a bug. It *should* be
> possible to do almost any reasonable opcode. For instance, reasonable
> possibilities include "write a byte to a pipe, open a file,
> install/rearrange some file descriptors, then exec".

-- 
Pavel Begunkov