Re: [PATCH v1 3/4] liburing: add helper for IORING_REGISTER_IOWAIT

[David Wei <dw@davidwei.uk>]

On 2024-02-24 07:29, Jens Axboe wrote:
> On 2/23/24 10:07 PM, David Wei wrote:
>> From: David Wei <davidhwei@meta.com>
>>
>> Sync include/liburing/io_uring.h and add io_uring_register_iowait()
>> helper function.
>>
>> Currently we unconditionally account time spent waiting for events in CQ
>> ring as iowait time.
>>
>> Some userspace tools consider iowait time to be CPU util/load which can
>> be misleading as the process is sleeping. High iowait time might be
>> indicative of issues for storage IO, but for network IO e.g. socket
>> recv() we do not control when the completions happen so its value
>> misleads userspace tooling.
>>
>> Add io_uring_register_iowait() which gates the previously unconditional
>> iowait accounting. By default time is not accounted as iowait, unless
>> this is explicitly enabled for a ring. Thus userspace can decide,
>> depending on the type of work it expects to do, whether it wants to
>> consider cqring wait time as iowait or not.
> 
> This looks fine, would you be up for writing the man page? If not. I can
> do it.

Oh shoot I totally forgot about that. Yeah, I'll write one up.