syscall path inward. A system call may select whether it needs the MP
lock or not (the default being that it does need it).
A great deal of conditional SMP code for various deadended experiments
has been removed. 'cil' and 'cml' have been removed entirely, and the
locking around the cpl has been removed. The conditional
separately-locked fast-interrupt code has been removed, meaning that
interrupts must hold the CPL now (but they pretty much had to anyway).
Another reason for doing this is that the original separate-lock for
interrupts just doesn't apply to the interrupt thread mechanism being
contemplated.
Modifications to the cpl may now ONLY occur while holding the MP
lock. For example, if an otherwise MP safe syscall needs to mess with
the cpl, it must hold the MP lock for the duration and must (as usual)
save/restore the cpl in a nested fashion.
This is precursor work for the real meat coming later: avoiding having
to hold the MP lock for common syscalls and I/O's and interrupt threads.
It is expected that the spl mechanisms and new interrupt threading
mechanisms will be able to run in tandem, allowing a slow piecemeal
transition to occur.
This patch should result in a moderate performance improvement due to
the considerable amount of code that has been removed from the critical
path, especially the simplification of the spl*() calls. The real
performance gains will come later.
Approved by: jkh
Reviewed by: current, bde (exception.s)
Some work taken from: luoqi's patch
fixes some namespace pollution in general and breakage of modules that
aren't in the sys tree in particular (<machine/ipl.h> includes further
headers that aren't installed under /usr/include).
Reimplemented SPLASSERT() so that it is more machine independent and
less bloated and doesn't require the <machine/ipl.h> include spam.
In particular, don't assume that `cpl' can be printed using %08x
format. The alpha arch doesn't even have `cpl'. SPLASSERT() was
harmless on alphas because it isn't actually used.
unless both "option INVARIANTS" and "options INVARIANT_SUPPORT"
are defined in the kernel's config(8) file.
SPLASSERT(expression, msg) used KASSERT to check that the
expression is true, panic()ing the kernel otherwise.
Approved by: jkh
Reviewed by: jdp, dfr, phk, eivind and green
Change "void *" to "volatile TYPE *", improving type safety
and eliminating some warnings (e.g., mp_machdep.c rev 1.106).
cpufunc.h:
Eliminate setbits. As defined, it's not precisely correct;
and it's redundant. (Use atomic_set_int instead.)
ipl_funcs.c:
Use atomic_set_int instead of setbits.
systm.h:
Include atomic.h.
Reviewed by: bde
surrounding critical sections that consist of (1) a single read or
(2) a single locked RMW operation.
(Thanks to thomma@slip.net (Tamiji Homma) for helping to test
these changes.)
implicitly LOCK'ed instruction), so there shouldn't be any harm in making
it volatile pointer compatable for one of the users of it. It seems to
generate the same code regardless.
- %fs register is added to trapframe and saved/restored upon kernel entry/exit.
- Per-cpu pages are no longer mapped at the same virtual address.
- Each cpu now has a separate gdt selector table. A new segment selector
is added to point to per-cpu pages, per-cpu global variables are now
accessed through this new selector (%fs). The selectors in gdt table are
rearranged for cache line optimization.
- fask_vfork is now on as default for both UP and SMP.
- Some aio code cleanup.
Reviewed by: Alan Cox <alc@cs.rice.edu>
John Dyson <dyson@iquest.net>
Julian Elischer <julian@whistel.com>
Bruce Evans <bde@zeta.org.au>
David Greenman <dg@root.com>
Interrupts under the new scheme are managed by the i386 nexus with the
awareness of the resource manager. There is further room for optimizing
the interfaces still. All the users of register_intr()/intr_create()
should be gone, with the exception of pcic and i386/isa/clock.c.
Added a new variable, 'bsp_apic_ready', which is set as soon as the bootstrap
CPU has initialized its local APIC. Conditionalize the GENSPLR functions
to call ss_lock ONLY after bsp_apic_ready is TRUE; This should prevent
any problems with races between the time the 1st AP becomes ready and the
time smp_active is set.
region protected by the simplelock 'cpl_lock'.
Notes:
- this code is currently controlled on a section by section basis with
defines in machine/param.h. All sections are currently enabled.
- this code is not as clean as I would like, but that can wait till later.
- the "giant lock" still surrounds most instances of this "cpl region".
I still have to do the code that arbitrates setting cpl between the
top and bottom halves of the kernel.
- the possibility of deadlock exists, I am committing the code at this
point so as to exercise it and detect any such cases B4 the "giant lock"
is removed.
Several new fine-grained locks.
New FAST_INTR() methods:
- separate simplelock for FAST_INTR, no more giant lock.
- FAST_INTR()s no longer checks ipending on way out of ISR.
sio made MP-safe (I hope).
rather than inlines. These are compiled with -fomit-frame-pointer and
work out pretty close to the original routines, but it might be a fraction
slower. The reason for doing this is to prevent the SWI_* and HWI_* values
from being compiled into drivers and lkms etc which is one of the things
that prevents the same lkm from being used on both SMP and UP kernels.
This gives us a lot more scope for experimenting with the splxxx
implementaton for SMP parallelism etc.
Reviewed by: bde
