Re: [PATCH] iov_iter: optimise iter type checking

Pavel Begunkov
2021-01-28T11:44:09Z

On 27/01/2021 18:31, Al Viro wrote:
> On Wed, Jan 27, 2021 at 03:48:10PM +0000, Pavel Begunkov wrote:
>> On 16/01/2021 05:18, Al Viro wrote:
>>> On Sat, Jan 09, 2021 at 10:11:09PM +0000, Pavel Begunkov wrote:
>>>
>>>>> Does any code actually look at the fields as a pair?
>>>>> Would it even be better to use separate bytes?
>>>>> Even growing the on-stack structure by a word won't really matter.
>>>>
>>>> u8 type, rw;
>>>>
>>>> That won't bloat the struct. I like the idea. If used together compilers
>>>> can treat it as u16.
>>>
>>> Reasonable, and from what I remember from looking through the users,
>>> no readers will bother with looking at both at the same time.
>>
>> Al, are you going turn it into a patch, or prefer me to take over?
>
> I'll massage that a bit and put into #work.iov_iter - just need to dig my
> way from under the pile of ->d_revalidate() review...

Perfect, thanks

--
Pavel Begunkov