Re: [PATCH 2/3] io_uring: change io_get_ext_arg() to uaccess begin + end

[Jens Axboe <axboe@kernel.dk>]

On 10/22/24 4:40 PM, Keith Busch wrote:
> On Tue, Oct 22, 2024 at 02:39:03PM -0600, Jens Axboe wrote:
>> In scenarios where a high frequency of wait events are seen, the copy
>> of the struct io_uring_getevents_arg is quite noticeable in the
>> profiles in terms of time spent. It can be seen as up to 3.5-4.5%.
>> Rewrite the copy-in logic, saving about 0.5% of the time.
> 
> I'm surprised it's faster to retrieve field by field instead of a
> straight copy. But you can't argue with the results!

It's a pretty common setup - mostly when copying separate entities. But
works here too!

> I was looking for the 'goto' for this label and discovered it's in the
> macro. Neat.
> 
> Reviewed-by: Keith Busch <kbusch@kernel.org>

Thanks, will add.

-- 
Jens Axboe