- Remove PCU_KERNEL (hi matt!) and significantly simplify the code.
This experimental feature was tried on ARM did not meet the expectations.
It may be revived one day, but it should be done in a much simpler way.
- Add a message structure for xcall function, pass the LWP ower and thus
optimise a race condition: if LWP is discarding its state on a remote CPU,
but another LWP already did it - do not cause an unecessary re-faulting.
- Reduce the variety of flags for PCU operations (only PCU_VALID and
PCU_REENABLE are used now), pass them only to the pcu_state_load().
- Rename pcu_used_p() to pcu_valid_p(); hopefully it is less confusing.
- pcu_save_all_on_cpu: SPL ought to be used here.
- Update and improve the pcu(9) man page; it needs wizd(8) though.
Adjust pcu(9) to this xcall(9) change. This may fix the problems after
x86 FPU was converted to use PCU, since it avoids heavy contention at the
lower levels (particularly, IPL_SOFTNET). This is a good illustration why
software interrupts should generally avoid any blocking on locks.
current CPU, and use it if a CPU is taken offline
-add a bool argument to pcu_discard which tells whether the internal
"LWP has used the coprocessor" flag should be set or reset. The flag
is reported by pcu_used_p(). If set, future accesses should use the
state stored in the PCB. If reset, it should be reset to default.
The former case is useful for setmcontext().
With that, it should not be necessary anymore to manage the "FPU used"
state by an additional MD variable.
approved by matt
is to provide routines that do as KASSERT(9) says: append a message
to the panic format string when the assertion triggers, with optional
arguments.
Fix call sites to reflect the new definition.
Discussed on tech-kern@. See
http://mail-index.netbsd.org/tech-kern/2011/09/07/msg011427.html
into LSSUSPENDED state, have that LWP save its PCU state for the coredump and
release its PCU status since its probably going to be exiting very soon.
Make pcu_save_all tolerate for being called for non-curlwp if that lwp belongs
to the same process, has a state of LSSUSPENDED, and no PCUs are in use.
Make the MD coredump code use pcu_save_all(l) since it'll need to save all
the PCU state anyways and can take advantage of the above tests.
- Add pcu_ops_t::pcu_state_release() operation for PCU_RELEASE case.
- Add pcu_switchpoint() to perform release operation on context switch.
- Sprinkle const, misc. Also, sync MIPS with changes.
Per discussions with matt@.
per CPU context tied with an LWP. Main use - lazy FPU handling on SMP.
Requested by matt@, will be used on mips64. Note: implementation will
be improved to use IPIs before adopting on x86. OK ad@.
rmind