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

[Jens Axboe <axboe@kernel.dk>]

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.

-- 
Jens Axboe