Add a pre-emption counter, td_generation, so that threads can notice
when they have been pre-empted by other threads. This is bumped from
within mi_switch() every time a context switch takes place.

Add a pre-emption counter, td_generation, so that threads can notice
when they have been pre-empted by other threads. This is bumped from
within mi_switch() every time a context switch takes place.

Discussed with: pete

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- On my Pentium4-M laptop, invalpg takes ~1100 cycles if the page is found in
the TLB and ~1600 if it is not. Therefore, it is more effecient to
invalidate the TLB after operations that use CM

- On my Pentium4-M laptop, invalpg takes ~1100 cycles if the page is found in
the TLB and ~1600 if it is not. Therefore, it is more effecient to
invalidate the TLB after operations that use CMAP rather than before.
- So that the tlb is invalidated prior to switching off of a processor, we
must change the switchin functions to switchout functions.
- Remove td_switchout from the thread and move it to the x86 pcb.
- Move the code that calls switchout into swtch.s. These changes make this
optimization truely x86 specific.

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Change instances of callout_init that specify MPSAFE behaviour to
use CALLOUT_MPSAFE instead of "1" for the second parameter. This
does not change the behaviour; it just makes the intent more clear.

- Various style fixes in both code and comments.
- Update some stale comments.
- Sort a couple of includes.
- Only set 'newcpu' in updatepri() if we use it.
- No functional changes.

Obtained from: b

- Various style fixes in both code and comments.
- Update some stale comments.
- Sort a couple of includes.
- Only set 'newcpu' in updatepri() if we use it.
- No functional changes.

Obtained from: bde (via an old diff I got a long time ago)

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Update powerpc to use the (old thread,new thread) calling convention
for cpu_throw() and cpu_switch().

- Convert Alpha over to the new calling conventions for cpu_throw() and
cpu_switch() where both the old and new threads are passed in as
arguments. Only powerpc uses the old conventions now.
- U

- Convert Alpha over to the new calling conventions for cpu_throw() and
cpu_switch() where both the old and new threads are passed in as
arguments. Only powerpc uses the old conventions now.
- Update comments in the Alpha swtch.s to reflect KSE changes.

Tested by: obrien, marcel

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unifdef -DLAZY_SWITCH and start to tidy up the associated glue.

o Change kse_thr_interrupt to allow send a signal to a specified thread,
or unblock a thread in kernel, and allow UTS to specify whether syscall
should be restarted.
o Add ability for UTS to moni

o Change kse_thr_interrupt to allow send a signal to a specified thread,
or unblock a thread in kernel, and allow UTS to specify whether syscall
should be restarted.
o Add ability for UTS to monitor signal comes in and removed from process,
the flag PS_SIGEVENT is used to indicate the events.
o Add a KMF_WAITSIGEVENT for KSE mailbox flag, UTS call kse_release with
this flag set to wait for above signal event.
o For SA based thread, kernel masks all signal in its signal mask, let
UTS to use kse_thr_interrupt interrupt a thread, and install a signal
frame in userland for the thread.
o Add a tm_syncsig in thread mailbox, when a hardware trap occurs,
it is used to deliver synchronous signal to userland, and upcall
is schedule, so UTS can process the synchronous signal for the thread.

Reviewed by: julian (mentor)

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Tidy up leftover lazy_switch instrumentation that is no longer needed.
This cleans up some #ifdef hell.

Rename P_THREADED to P_SA. P_SA means a process is using scheduler
activations.

Use __FBSDID().

Add a couple of XXX comments where the intent is not clear.

Found by: FlexeLint

Revamp of the syscall path, exception and context handling. The
prime objectives are:
o Implement a syscall path based on the epc inststruction (see
sys/ia64/ia64/syscall.s).
o Revisit the place

Revamp of the syscall path, exception and context handling. The
prime objectives are:
o Implement a syscall path based on the epc inststruction (see
sys/ia64/ia64/syscall.s).
o Revisit the places were we need to save and restore registers
and define those contexts in terms of the register sets (see
sys/ia64/include/_regset.h).

Secundairy objectives:
o Remove the requirement to use contigmalloc for kernel stacks.
o Better handling of the high FP registers for SMP systems.
o Switch to the new cpu_switch() and cpu_throw() semantics.
o Add a good unwinder to reconstruct contexts for the rare
cases we need to (see sys/contrib/ia64/libuwx)

Many files are affected by this change. Functionally it boils
down to:
o The EPC syscall doesn't preserve registers it does not need
to preserve and places the arguments differently on the stack.
This affects libc and truss.
o The address of the kernel page directory (kptdir) had to
be unstaticized for use by the nested TLB fault handler.
The name has been changed to ia64_kptdir to avoid conflicts.
The renaming affects libkvm.
o The trapframe only contains the special registers and the
scratch registers. For syscalls using the EPC syscall path
no scratch registers are saved. This affects all places where
the trapframe is accessed. Most notably the unaligned access
handler, the signal delivery code and the debugger.
o Context switching only partly saves the special registers
and the preserved registers. This affects cpu_switch() and
triggered the move to the new semantics, which additionally
affects cpu_throw().
o The high FP registers are either in the PCB or on some
CPU. context switching for them is done lazily. This affects
trap().
o The mcontext has room for all registers, but not all of them
have to be defined in all cases. This mostly affects signal
delivery code now. The *context syscalls are as of yet still
unimplemented.

Many details went into the removal of the requirement to use
contigmalloc for kernel stacks. The details are mostly CPU
specific and limited to exception_save() and exception_restore().
The few places where we create, destroy or switch stacks were
mostly simplified by not having to construct physical addresses
and additionally saving the virtual addresses for later use.

Besides more efficient context saving and restoring, which of
course yields a noticable speedup, this also fixes the dreaded
SMP bootup problem as a side-effect. The details of which are
still not fully understood.

This change includes all the necessary backward compatibility
code to have it handle older userland binaries that use the
break instruction for syscalls. Support for break-based syscalls
has been pessimized in favor of a clean implementation. Due to
the overall better performance of the kernel, this will still
be notived as an improvement if it's noticed at all.

Approved by: re@ (jhb)

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- Merge struct procsig with struct sigacts.
- Move struct sigacts out of the u-area and malloc() it using the
M_SUBPROC malloc bucket.
- Add a small sigacts_*() API for managing sigacts structures:

- Merge struct procsig with struct sigacts.
- Move struct sigacts out of the u-area and malloc() it using the
M_SUBPROC malloc bucket.
- Add a small sigacts_*() API for managing sigacts structures: sigacts_alloc(),
sigacts_free(), sigacts_copy(), sigacts_share(), and sigacts_shared().
- Remove the p_sigignore, p_sigacts, and p_sigcatch macros.
- Add a mutex to struct sigacts that protects all the members of the struct.
- Add sigacts locking.
- Remove Giant from nosys(), kill(), killpg(), and kern_sigaction() now
that sigacts is locked.
- Several in-kernel functions such as psignal(), tdsignal(), trapsignal(),
and thread_stopped() are now MP safe.

Reviewed by: arch@
Approved by: re (rwatson)

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Remove TD_ON_RUNQ() from a check to make sure Giant is not held when
calling mi_switch(). The kernel would panic on an earlier KASSERT() in
mi_switch() if TD_ON_RUNQ() was true.

Garbage collect unused TDF_INMSLEEP flag.

AMD64 uses the new-style cpu_switch()/cpu_throw() calling conventions.

- Protect p_numthreads with the sched_lock.
- Protect p_singlethread with both the sched_lock and the proc lock.
- Protect p_suspcount with the proc lock.

Commit a partial lazy thread switch mechanism for i386. it isn't as lazy
as it could be and can do with some more cleanup. Currently its under
options LAZY_SWITCH. What this does is avoid %cr3 rel

Commit a partial lazy thread switch mechanism for i386. it isn't as lazy
as it could be and can do with some more cleanup. Currently its under
options LAZY_SWITCH. What this does is avoid %cr3 reloads for short
context switches that do not involve another user process. ie: we can
take an interrupt, switch to a kthread and return to the user without
explicitly flushing the tlb. However, this isn't as exciting as it could
be, the interrupt overhead is still high and too much blocks on Giant
still. There are some debug sysctls, for stats and for an on/off switch.

The main problem with doing this has been "what if the process that you're
running on exits while we're borrowing its address space?" - in this case
we use an IPI to give it a kick when we're about to reclaim the pmap.

Its not compiled in unless you add the LAZY_SWITCH option. I want to fix a
few more things and get some more feedback before turning it on by default.

This is NOT a replacement for Bosko's lazy interrupt stuff. This was more
meant for the kthread case, while his was for interrupts. Mine helps a
little for interrupts, but his helps a lot more.

The stats are enabled with options SWTCH_OPTIM_STATS - this has been a
pseudo-option for years, I just added a bunch of stuff to it.

One non-trivial change was to select a new thread before calling
cpu_switch() in the first place. This allows us to catch the silly
case of doing a cpu_switch() to the current process. This happens
uncomfortably often. This simplifies a bit of the asm code in cpu_switch
(no longer have to call choosethread() in the middle). This has been
implemented on i386 and (thanks to jake) sparc64. The others will come
soon. This is actually seperate to the lazy switch stuff.

Glanced at by: jake, jhb

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- Borrow the KSE single threading code for exec and exit. We use the check
if (p->p_numthreads > 1) and not a flag because action is only necessary
if there are other threads. The rest of the

- Borrow the KSE single threading code for exec and exit. We use the check
if (p->p_numthreads > 1) and not a flag because action is only necessary
if there are other threads. The rest of the system has no need to
identify thr threaded processes.
- In kern_thread.c use thr_exit1() instead of thread_exit() if P_THREADED
is not set.

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Adjust code for userland preemptive. Userland can set a quantum in
kse_mailbox to schedule an upcall, this is useful for userland timeout
routine, for example pthread_cond_timedwait().

Also extract

Adjust code for userland preemptive. Userland can set a quantum in
kse_mailbox to schedule an upcall, this is useful for userland timeout
routine, for example pthread_cond_timedwait().

Also extract upcall scheduling code from kse_reassign and create
a new function called thread_switchout to include these code.

Reviewed by: julain

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Replace calls to WITNESS_SLEEP() and witness_list() with equivalent calls
to WITNESS_WARN().

When a process has been waiting on a condition variable or mutex the
td_wmesg field in the thread structure points to the description string of
the condition variable or mutex. If the condvar or the

When a process has been waiting on a condition variable or mutex the
td_wmesg field in the thread structure points to the description string of
the condition variable or mutex. If the condvar or the mutex had been
initialized from a loadable module that was unloaded in the meantime,
td_wmesg may now point to invalid memory. Retrieving the process table now
may panic the kernel (or access junk). Setting the td_wmesg field to NULL
after unblocking on the condvar/mutex prevents this panic.

PR: kern/47408
Approved by: jake (mentor)

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Change the process flags P_KSES to be P_THREADED.
This is just a cosmetic change but I've been meaning to do it for about a year.

Move a bunch of flags from the KSE to the thread.
I was in two minds as to where to put them in the first case..
I should have listenned to the other mind.

Submitted by: parts by davidxu@
Reviewed

Move a bunch of flags from the KSE to the thread.
I was in two minds as to where to put them in the first case..
I should have listenned to the other mind.

Submitted by: parts by davidxu@
Reviewed by: jeff@ mini@

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