CVS log for src/sys/sys/syncobj.h

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sys/lwp.h: Nix sys/syncobj.h dependency.

Remove it in ddb/db_syncobj.h too.

New sys/wchan.h defines wchan_t so that users need not pull in
sys/syncobj.h to get it.

Sprinkle #include <sys/syncobj.h> in .c files where it is now needed.

Ensure that an LWP that has taken a legitimate wakeup never produces an
error code from sleepq_block().  Then, it's possible to make cv_signal()
work as expected and only ever wake a singular LWP.

- Simplify how priority boost for blocking in kernel is handled.  Rather
  than setting it up at each site where we block, make it a property of
  syncobj_t.  Then, do not hang onto the priority boost until userret(),
  drop it as soon as the LWP is out of the run queue and onto a CPU.
  Holding onto it longer is of questionable benefit.

- This allows two members of lwp_t to be deleted, and mi_userret() to be
  simplified a lot (next step: trim it down to a single conditional).

- While here, constify syncobj_t and de-inline a bunch of small functions
  like lwp_lock() which turn out not to be small after all (I don't know
  why, but atomic_*_relaxed() seem to provoke a compiler shitfit above and
  beyond what volatile does).

sys/syncobj.h: Expose this to _KMEMUSER for future use by crash(8).

This will allow crash(8) to get at the syncobj name.

kern: New struct syncobj::sobj_name member for diagnostics.

XXX potential kernel ABI change -- not sure any modules actually use
struct syncobj but it's hard to rule that out because sys/syncobj.h
leaks into sys/lwp.h

Merge changes from current as of 20200406

SOBJ_SLEEPQ_FIFO is gone

Cosmetic tweak

Sync with head.

kpause(): is only awoken via timeout or signal, so use SOBJ_SLEEPQ_NULL like
_lwp_park() does, and dispense with the hashed sleepq & lock.

- List all of the syncobjs in syncobj.h.
- Update a comment.

Add SOBJ_SLEEPQ_NULL: means there is no TAILQ and the caller tracks the
sleeping LWPs some other way, which sleepq_*() doesn't know about.

sync with head

Remove uarea swap-out functionality:

- Addresses the issue described in PR/38828.
- Some simplification in threading and sleepq subsystems.
- Eliminates pmap_collect() and, as a side note, allows pmap optimisations.
- Eliminates XS_CTL_DATA_ONSTACK in scsipi code.
- Avoids few scans on LWP list and thus potentially long holds of proc_lock.
- Cuts ~1.5k lines of code.  Reduces amd64 kernel size by ~4k.
- Removes __SWAP_BROKEN cases.

Tested on x86, mips, acorn32 (thanks <mpumford>) and partly tested on
acorn26 (thanks to <bjh21>).

Discussed on <tech-kern>, reviewed by <ad>.

Sync with HEAD.

sync with head.

sync with head.

Remove clause 3 and 4 from TNF licenses

Sync with HEAD.

Declare sleep_syncobj.

sync with head.

sync with head.

sync with HEAD

Add a boolean parameter to syncobj_t::sobj_unsleep. If true we want the
existing behaviour: the unsleep method unlocks and wakes the swapper if
needs be. If false, the caller is doing a batch operation and will take
care of that later. This is kind of ugly, but it's difficult for the caller
to know which lock to release in some situations.

sync with HEAD

sync with head.

Sync with HEAD.

Sync with HEAD.

Sync with _lwp_park/priority changes on HEAD.

- Fix sleepq_block() to return EINTR if the LWP is cancelled. Pointed out
  by yamt@.

- Introduce SOBJ_SLEEPQ_LIFO, and use for LWPs sleeping via _lwp_park.
  libpthread enqueues most waiters in LIFO order to try and wake LWPs that
  ran recently, since their working set is more likely to be in cache.
  Matching the order of insertion reduces the time spent searching queues
  in the kernel.

- Do not boost the priority of LWPs sleeping in _lwp_park, just let them
  sleep at their user priority level. LWPs waiting for some I/O event in
  the kernel still wait with kernel priority and get woken more quickly.
  This needs more evaluation and is to be revisited, but the effect on a
  variety of benchmarks is positive.

- When waking LWPs, do not send an IPI to remote CPUs or arrange for the
  current LWP to be preempted unless (a) the thread being awoken has kernel
  priority and has higher priority than the currently running thread or (b)
  the remote CPU is idle.

sync with head.

- sync with head.
- move sched_changepri back to kern_synch.c as it doesn't know PPQ anymore.

file syncobj.h was added on branch yamt-lazymbuf on 2007-09-03 14:46:38 +0000

file syncobj.h was added on branch yamt-idlelwp on 2007-02-27 16:55:17 +0000

typedef pri_t and use it instead of int and u_char.

Fix copyright at yamt's request.

move wchan_t and syncobj_t to a dedicated header to simplify dependencies.
fix "XXX wchan_t".