I see no reason why punting is not always better.
Waitfd does not support NO_WAIT or poll therefore the request must be
always punted to the io_wq anyway.

The WaitfdSleepStrategy did not gather the amount of posted notifications
but the PipeSleepStrategy did.
Move the stats accounting into AbstractIoSleepStrategy so all derived
strategies track the amount of written notifications.

Set the user_data to NewWorkNotification on the MSG_RING cqe to detect
a possible failure (operation not supported by the kernel).

IOURING_OP_MSG_RING will creates two cqes on probably different rings.
We do not need the cqe on the submitting ring therefore skip its
generation and only track that on the messaged ring an additional cqe
is expected.

When the custom logic of the IO-based sleep strategies returns
false we already have set the sleeper state to Sleeping and must
reset it.

With Linux 5.18 io_uring supports sending notifications between io_urings.
This removes the need of writing to a specific eventfd to notify
specific sleeping workers.
This greatly reduces the complexity of the sued algorithm because
we do not longer need to prepare two sleeps in an atomic way.

The notify specific algorithm no can be similar to the one used by the
semaphore implementation.
The notifier sets the state of the specific worker to Notified and
if its was previously sleeping it is responsible to send a wakeup
message.

When a worker is going to sleep it sets its state to Running if
it was notified the state is reset and the sleep attempt skipped.
Otherwise a global read is prepared if needed and the worker waits
on its io_uring.

449 is futex_waitv since linux 5.16.

Eventfds are pollable (no iow thread is blocked reading from the IO object)
contrary to waitfds.
And using pipes seams also rather excessive especially since we ensure
that only a single notification is written before it is consumed.

This makes the code of the IO-based sleep strategies easier and I would
expect also faster.

Introduce AbstractIoSleepStrategy holding most of the code needed for
a sleep strategy using an IO object fur suspension/notification.

This changes are used in future patches to implement more IO-based
sleep strategies.

Add the Big Fancy Pulser 9000 (BFP 9K) evaluation

See merge request i4/manycore/emper!397

[README] Fibirl uses spawn/sync as keywords (and no longer fork/join)

See merge request i4/manycore/emper!403

[io/Stats] For AlarmFutures (TIMEOUT) expect them to return ETIME

See merge request i4/manycore/emper!402

[Makefile] Add asan(-test) targets

See merge request i4/manycore/emper!398

LTO

See merge request i4/manycore/emper!401

This prevents a linker error because of undefined symbols when LTO is
used.

[Runtime] Switch logging of env var handling from DBG() to LOGI()

See merge request i4/manycore/emper!400

Also use std::boolalpha to print ture/false.

[SpuriousFutex2Semaphore] Add missing emper-config.h include

See merge request i4/manycore/emper!399

Fixes: f4e72a97 ("[iwyu] Fix includes as per iwyu 0.18")

[ContextManager] Remove the put/get free context cycle

See merge request i4/manycore/emper!396

The put/get free context cycle in ContextManager::start() (if
continuation stealing is enabled) became unnecessary with
c66551bf ("[Context] Use 'jmp' instead of 'ret' to kickoff the
context").