Re: [PATCH v3 0/4] fast poll multishot mode

Jens Axboe
2022-05-07T15:29:05Z

On 5/7/22 8:06 AM, Hao Xu wrote:
> Let multishot support multishot mode, currently only add accept as its
> first comsumer.

consumer

> theoretical analysis:
> 1) when connections come in fast
> - singleshot:
> add accept sqe(userpsace) --> accept inline

userspace

> ^ |
> |-----------------|
> - multishot:
> add accept sqe(userspace) --> accept inline
> ^ |
> |--*--|
>
> we do accept repeatedly in * place until get EAGAIN
>
> 2) when connections come in at a low pressure
> similar thing like 1), we reduce a lot of userspace-kernel context
> switch and useless vfs_poll()

Overall this looks better than v2 for sure, just some minor tweaks
needed I believe.

But we still need to consider direct accept with multishot... Should
probably be an add-on patch as I think it'd get a bit more complicated
if we need to be able to cheaply find an available free fixed fd slot.
I'll try and play with that.

--
Jens Axboe