Clear ps_xsig when continuing after a PS_TRACED stop.

Also remove the ps_xsig handling in setrunnable() it is in the wrong spot
and causes signals to be delivered over and over again.

Attaching to

Clear ps_xsig when continuing after a PS_TRACED stop.

Also remove the ps_xsig handling in setrunnable() it is in the wrong spot
and causes signals to be delivered over and over again.

Attaching to an already stopped process is affected by this. The SIGSTOP
sent by ptrace is now ignored in ptsignal() and as a result gdb will hang
in wait4() until a SIGCONT is delivered to the process. After that all
works as usual.

OK mpi@

show more ...

Move common code to update the proc runtime into tuagg_add_runtime().

OK mpi@ kn@

Rework per proc and per process time usage accounting

For procs (threads) the accounting happens now lockless by curproc using
a generation counter. Callers need to use tu_enter() and tu_leave() for

Rework per proc and per process time usage accounting

For procs (threads) the accounting happens now lockless by curproc using
a generation counter. Callers need to use tu_enter() and tu_leave() for this.
To read the proc p_tu struct tuagg_get_proc() should be used. It ensures
that the values read is consistent.

For processes only the time of exited threads is accumulated in ps_tu and
to get the proper process time usage tuagg_get_process() needs to be called.
tuagg_get_process() will sum up all procs p_tu plus the ps_tu.

This removes another SCHED_LOCK() dependency. Adjust the code in
exit1() and exit2() to correctly account for the full run time.
For this adjust sched_exit() to do the runtime accounting like it is done
in mi_switch().

OK jca@ dlg@

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Remove the now unsued s argument to SCHED_LOCK and SCHED_UNLOCK.

The SPL level is not tacked by the mutex and we no longer need to track
this in the callers.
OK miod@ mlarkin@ tb@ jca@

Convert SCHED_LOCK from a recursive kernel lock to a mutex.

Over the last weeks the last SCHED_LOCK recursion was removed so this
is now possible and will allow to split up the SCHED_LOCK in a upcom

Convert SCHED_LOCK from a recursive kernel lock to a mutex.

Over the last weeks the last SCHED_LOCK recursion was removed so this
is now possible and will allow to split up the SCHED_LOCK in a upcoming
step.

Instead of implementing an MP and SP version of SCHED_LOCK this just
always uses the mutex implementation.
While this makes the local s argument unused (the spl is now tracked by
the mutex itself) it is still there to keep this diff minimal.

Tested by many.
OK jca@ mpi@

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Prevent a recursion inside wakeup(9) when scheduler tracepoints are enabled.

Tracepoints like "sched:enqueue" and "sched:unsleep" were called from inside
the loop iterating over sleeping threads as

Prevent a recursion inside wakeup(9) when scheduler tracepoints are enabled.

Tracepoints like "sched:enqueue" and "sched:unsleep" were called from inside
the loop iterating over sleeping threads as part of wakeup_proc(). When such
tracepoints were enabled they could result in another wakeup(9) possibly
corrupting the sleepqueue.

Rewrite wakeup(9) in two stages, first dequeue threads from the sleepqueue then
call setrunnable() and possible tracepoints for each of them.

This requires moving unsleep() outside of setrunnable() because it messes with
the sleepqueue.

ok claudio@

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clockintr: switch from callee- to caller-allocated clockintr structs

Currently, clockintr_establish() calls malloc(9) to allocate a
clockintr struct on behalf of the caller. mpi@ says this behavior

clockintr: switch from callee- to caller-allocated clockintr structs

Currently, clockintr_establish() calls malloc(9) to allocate a
clockintr struct on behalf of the caller. mpi@ says this behavior is
incompatible with dt(4). In particular, calling malloc(9) during the
initialization of a PCB outside of dt_pcb_alloc() is (a) awkward and
(b) may conflict with future changes/optimizations to PCB allocation.

To side-step the problem, this patch changes the clockintr subsystem
to use caller-allocated clockintr structs instead of callee-allocated
structs.

clockintr_establish() is named after softintr_establish(), which uses
malloc(9) internally to create softintr objects. The clockintr subsystem
is no longer using malloc(9), so the "establish" naming is no longer apt.
To avoid confusion, this patch also renames "clockintr_establish" to
"clockintr_bind".

Requested by mpi@. Tweaked by mpi@.

Thread: https://marc.info/?l=openbsd-tech&m=170597126103504&w=2

ok claudio@ mlarkin@ mpi@

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clockintr: move callback-specific API behaviors to "clockrequest" namespace

The API's behavior when invoked from a callback function is impossible
to document. Move the special behavior into a dist

clockintr: move callback-specific API behaviors to "clockrequest" namespace

The API's behavior when invoked from a callback function is impossible
to document. Move the special behavior into a distinct namespace,
"clockrequest".

- Add a 'struct clockrequest'. Basically a stripped-down 'struct clockintr'
for exclusive use during clockintr_dispatch().
- In clockintr_queue, replace the "cq_shadow" clockintr with a "cq_request"
clockrequest. They serve the same purpose.
- CLST_SHADOW_PENDING -> CR_RESCHEDULE; different namespace, same meaning.
- CLST_IGNORE_SHADOW -> CLST_IGNORE_REQUEST; same meaning.
- Move shadow branch in clockintr_advance() to clockrequest_advance().
- clockintr_request_random() becomes clockrequest_advance_random().
- Delete dead shadow branches in clockintr_cancel(), clockintr_schedule().
- Callback functions now get a clockrequest pointer instead of a special
clockintr pointer: update all prototypes, callers.

No functional change intended.

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kernel: expand fixed clock interrupt periods to 64-bit values

Technically, all the current fixed clock interrupt periods fit within
an unsigned 32-bit value. But 32-bit multiplication is an acciden

kernel: expand fixed clock interrupt periods to 64-bit values

Technically, all the current fixed clock interrupt periods fit within
an unsigned 32-bit value. But 32-bit multiplication is an accident
waiting to happen. So, expand the fixed periods for hardclock,
statclock, profclock, and roundrobin to 64-bit values.

One exception: statclock_mask remains 32-bit because random(9) yields
32-bit values. Update the initclocks() comment to make it clear that
this is not an accident.

show more ...

scheduler_start: move static timeout structs into callback functions

Move the schedcpu() and update_loadavg() timeout structs from
scheduler_start() into their respective callback functions and
stat

scheduler_start: move static timeout structs into callback functions

Move the schedcpu() and update_loadavg() timeout structs from
scheduler_start() into their respective callback functions and
statically initialize them with TIMEOUT_INITIALIZER(9).

The structs are already hidden from the global namespace and the
timeouts are already self-managing, so we may as well fully
consolidate things.

Thread: https://marc.info/?l=openbsd-tech&m=169488184019047&w=2

"Sure." claudio@

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clockintr: support an arbitrary callback function argument

Callers can now provide an argument pointer to clockintr_establish().
The pointer is kept in a new struct clockintr member, cl_arg. The
po

clockintr: support an arbitrary callback function argument

Callers can now provide an argument pointer to clockintr_establish().
The pointer is kept in a new struct clockintr member, cl_arg. The
pointer is passed as the third parameter to clockintr.cl_func when it
is executed during clockintr_dispatch(). Like the callback function,
the callback argument is immutable after the clockintr is established.

At present, nothing uses this. All current clockintr_establish()
callers pass a NULL arg pointer. However, I am confident that dt(4)'s
profile provider will need this in the near future.

Requested by dlg@ back in March.

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Preempt a running proc even if there is no other process/thread queued
on that CPU's runqueue. This way mi_switch() is invoked which is necessary
to a) signal srm that the cpu changed context b) runt

Preempt a running proc even if there is no other process/thread queued
on that CPU's runqueue. This way mi_switch() is invoked which is necessary
to a) signal srm that the cpu changed context b) runtime stats are updated
c) requests to stop the CPU are checked.
This should fix the issue reported by Eric Wong (e at 80x24 org) that
RLIMIT_CPU is unreliable on idle systems.
OK kettenis@ cheloha@

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Remove p_rtime from struct proc and replace it by passing the timespec
as argument to the tuagg_locked function.

- Remove incorrect use of p_rtime in other parts of the tree. p_rtime was
almost alwa

Remove p_rtime from struct proc and replace it by passing the timespec
as argument to the tuagg_locked function.

- Remove incorrect use of p_rtime in other parts of the tree. p_rtime was
almost always 0 so including it in any sum did not alter the result.
- In main() the update of time can be further simplified since at that time
only the primary cpu is running.
- Add missing nanouptime() call in cpu_hatch() for hppa
- Rename tuagg_unlocked to tuagg_locked like it is done in the rest of
the tree.

OK cheloha@ dlg@

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Refetch the spc pointer after cpu_switchto() since the value is stale
after the proc switch. With the value refetched the rest of the code
can be simplified.
Input guenther@, OK cheloha@, miod@

Move the loadavg calculation to sched_bsd.c as update_loadav()

With this uvm_meter() is no more and update_loadav() uses a simple timeout
instead of getting called via schedcpu().

OK deraadt@ mpi@

Move the loadavg calculation to sched_bsd.c as update_loadav()

With this uvm_meter() is no more and update_loadav() uses a simple timeout
instead of getting called via schedcpu().

OK deraadt@ mpi@ cheloha@

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Extend scheduler tracepoints to follow CPU jumping.

- Add two new tracpoints sched:fork & sched:steal
- Include selected CPU number in sched:wakeup
- Add sched:unsleep corresponding to sched:sleep w

Extend scheduler tracepoints to follow CPU jumping.

- Add two new tracpoints sched:fork & sched:steal
- Include selected CPU number in sched:wakeup
- Add sched:unsleep corresponding to sched:sleep which matches add/removal
of threads on the sleep queue

ok claudio@

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hardclock(9), roundrobin: make roundrobin() an independent clock interrupt

- Remove the roundrobin() call from hardclock(9).

- Revise roundrobin() to make it a valid clock interrupt callback.
It

hardclock(9), roundrobin: make roundrobin() an independent clock interrupt

- Remove the roundrobin() call from hardclock(9).

- Revise roundrobin() to make it a valid clock interrupt callback.
It is still periodic and it still runs at one tenth of the hardclock
frequency.

- Account for multiple expirations in roundrobin(): if two or more
roundrobin periods have elapsed, set SPCF_SHOULDYIELD on the running
thread immediately to simulate normal behavior.

- Each schedstate_percpu has its own roundrobin() handle, spc_roundrobin.
spc_roundrobin is started/advanced during clockintr_cpu_init().
Intervals elapsed across suspend/resume are discarded.

- rrticks_init and schedstate_percpu.spc_rrticks are now useless:
delete them.

Tweaked by mpi@. With input from mpi@ and claudio@.

Thread: https://marc.info/?l=openbsd-tech&m=169127381314651&w=2

ok mpi@ claudio@

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hardclock(9): move setitimer(2) code into itimer_update()

- Move the setitimer(2) code responsible for updating the ITIMER_VIRTUAL
and ITIMER_PROF timers from hardclock(9) into a new clock interru

hardclock(9): move setitimer(2) code into itimer_update()

- Move the setitimer(2) code responsible for updating the ITIMER_VIRTUAL
and ITIMER_PROF timers from hardclock(9) into a new clock interrupt
routine, itimer_update(). itimer_update() is periodic and runs at the
same frequency as the hardclock.

+ Revise itimerdecr() to run within itimer_mtx instead of entering
and leaving it.

- Each schedstate_percpu has its own itimer_update() handle, spc_itimer.
A new scheduler flag, SPCF_ITIMER, indicates whether spc_itimer was
started during the last mi_switch() and needs to be stopped during the
next mi_switch() or sched_exit().

- A new per-process flag, PS_ITIMER, indicates whether ITIMER_VIRTUAL
and/or ITIMER_PROF are running. Checking the flag is easier than
entering itimer_mtx to check process.ps_timer[]. The flag is set
and cleared in a new helper function, process_reset_itimer_flag().

- In setitimer(), call need_resched() when the state of ITIMER_VIRTUAL
or ITIMER_PROF is changed to force an mi_switch() and update
spc_itimer.

claudio@ notes that ITIMER_PROF could be implemented as a high-res
timer using the thread's execution time as a guide for when to
interrupt the process and assert SIGPROF. This would probably work
really well in single-threaded processes. ITIMER_VIRTUAL would be
more difficult to make high-res, though, as you need to exclude time
spent in the kernel.

Tested on powerpc64 by gkoehler@. With input from claudio@.

Thread: https://marc.info/?l=openbsd-tech&m=169038818517101&w=2

ok claudio@

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statclock: move profil(2), GPROF code to profclock(), gmonclock()

This patch isolates profil(2) and GPROF from statclock(). Currently,
statclock() implements both profil(2) and GPROF through a comp

statclock: move profil(2), GPROF code to profclock(), gmonclock()

This patch isolates profil(2) and GPROF from statclock(). Currently,
statclock() implements both profil(2) and GPROF through a complex
mechanism involving both platform code (setstatclockrate) and the
scheduler (pscnt, psdiv, and psratio). We have a machine-independent
interface to the clock interrupt hardware now, so we no longer need to
do it this way.

- Move profil(2)-specific code from statclock() to a new clock
interrupt callback, profclock(), in subr_prof.c. Each
schedstate_percpu has its own profclock handle. The profclock is
enabled/disabled for a given CPU when it is needed by the running
thread during mi_switch() and sched_exit().

- Move GPROF-specific code from statclock() to a new clock interrupt
callback, gmonclock(), in subr_prof.c. Where available, each cpu_info
has its own gmonclock handle . The gmonclock is enabled/disabled for
a given CPU via sysctl(2) in prof_state_toggle().

- Both profclock() and gmonclock() have a fixed period, profclock_period,
that is initialized during initclocks().

- Export clockintr_advance(), clockintr_cancel(), clockintr_establish(),
and clockintr_stagger() via <sys/clockintr.h>. They have external
callers now.

- Delete pscnt, psdiv, psratio. From schedstate_percpu, also delete
spc_pscnt and spc_psdiv. The statclock frequency is not dynamic
anymore so these variables are now useless.

- Delete code/state related to the dynamic statclock frequency from
kern_clockintr.c. The statclock frequency can still be pseudo-random,
so move the contents of clockintr_statvar_init() into clockintr_init().

With input from miod@, deraadt@, and claudio@. Early revisions
cleaned up by claudio. Early revisions tested by claudio@. Tested by
cheloha@ on amd64, arm64, macppc, octeon, and sparc64 (sun4v).
Compile- and boot- tested on i386 by mlarkin@. riscv64 compilation
bugs found by mlarkin@. Tested on riscv64 by jca@. Tested on
powerpc64 by gkoehler@.

show more ...

Rework sleep_setup()/sleep_finish() to no longer hold the scheduler lock
between calls.

Instead of forcing an atomic operation across multiple calls use a three
step transaction.
1. setup sleep stat

Rework sleep_setup()/sleep_finish() to no longer hold the scheduler lock
between calls.

Instead of forcing an atomic operation across multiple calls use a three
step transaction.
1. setup sleep state by calling sleep_setup()
2. recheck sleep condition to ensure that the event did not fire before
sleep_setup() registered the proc onto the sleep queue
3. call sleep_finish() to either sleep or keep on running based on the
step 2 outcome and any possible signal delivery

To make this work wakeup from signals, single thread api and wakeup(9) need
to be aware if a process is between step 1 and step 3 so that the process
is not enqueued back onto the runqueue while going to sleep. Introduce
the p_flag P_WSLEEP to detect this situation.

On top of this remove the spl dance in msleep() which is no longer required.
It is ok to process interrupts between step 1 and 3.

OK mpi@ cheloha@

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Revert "schedcpu, uvm_meter(9): make uvm_meter() an independent timeout"

Sometimes causes boot hang after mounting root partition.

Thread 1: https://marc.info/?l=openbsd-misc&m=168736497407357&w=2

Revert "schedcpu, uvm_meter(9): make uvm_meter() an independent timeout"

Sometimes causes boot hang after mounting root partition.

Thread 1: https://marc.info/?l=openbsd-misc&m=168736497407357&w=2
Thread 2: https://marc.info/?l=openbsd-misc&m=168737429214370&w=2

show more ...

schedcpu, uvm_meter(9): make uvm_meter() an independent timeout

uvm_meter(9) should not base its periodic uvm_loadav() call on the UTC
clock. It also no longer needs to periodically wake up proc0 b

schedcpu, uvm_meter(9): make uvm_meter() an independent timeout

uvm_meter(9) should not base its periodic uvm_loadav() call on the UTC
clock. It also no longer needs to periodically wake up proc0 because
proc0 doesn't do any work. schedcpu() itself may change or go away,
but as kettenis@ notes we probably can't completely remove the concept
of a "load average" from OpenBSD, given its long Unix heritage.

So, (1) remove the uvm_meter() call from schedcpu(), (2) make
uvm_meter() an independent timeout started alongside schedcpu() during
scheduler_start(), and (3) delete the vestigial periodic proc0 wakeup.

With input from deraadt@, kettenis@, and claudio@. deraadt@ cautions
that this change may confuse administrators who hold the load average
in high regard.

Thread: https://marc.info/?l=openbsd-tech&m=168710929409153&w=2

general agreement with this direction from kettenis@
ok claudio@

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kernel: stathz is always non-zero after cpu_initclocks()

Now that the clockintr switch is complete, cpu_initclocks() always
initializes stathz to a non-zero value. We don't call statclock()
from ha

kernel: stathz is always non-zero after cpu_initclocks()

Now that the clockintr switch is complete, cpu_initclocks() always
initializes stathz to a non-zero value. We don't call statclock()
from hardclock(9) anymore and, more broadly, we don't need to test
whether stathz is non-zero before using it.

With input from kettenis@.

Link: https://marc.info/?l=openbsd-tech&m=167434223309668&w=2

ok kettenis@ miod@

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zap a pile of dangling tabs

remove unneeded includes in sys/kern
ok mpi@ miod@