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
to use a locked cmpexg when unlocking a lock that we already hold, since
nobody else can touch the lock while we hold it. Second, it is not
necessary to use a locked cmpexg when locking a lock that we already
hold, for the same reason. These changes will allow MP locks to be used
recursively without impacting performance.
Modify two procedures that are called only by assembly and are already
NOPROF entries to pass a critical argument in %edx instead of on the
stack, removing a significant amount of code from the critical path
as a consequence.
Reviewed by: Alfred Perlstein <bright@wintelcom.net>, Peter Wemm <peter@netplex.com.au>
for elf kernels (it is broken for all kernels due to lack of egcs support).
Renaming of many assembler labels is avoided by declaring by declaring
the labels that need to be visible to gprof as having type "function"
and depending on the elf version of gprof being zealous about discarding
the others. A few type declarations are still missing, mainly for SMP.
PR: 9413
Submitted by: Assar Westerlund <assar@sics.se> (initial parts)
- %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>
instead of at compile time using ifdefs.
Use _swi_null instead of dummycamisr. CAM and dpt should call
register_swi() instead of hacking on ihandlers[] directly.
everything is contained inside #ifdef VM86, so this option must be
present in the config file to use this functionality.
Thanks to Tor Egge, these changes should work on SMP machines. However,
it may not be throughly SMP-safe.
Currently, the only BIOS calls made are memory-sizing routines at bootup,
these replace reading the RTC values.
interrupts are masked, and EOI is sent iff the corresponding ISR bit
is set in the local apic. If the CPU cannot obtain the interrupt
service lock (currently the global kernel lock) the interrupt is
forwarded to the CPU holding that lock.
Clock interrupts now have higher priority than other slow interrupts.
- A nonprofiling version of s_lock (called s_lock_np) is used
by mcount.
- When profiling is active, more registers are clobbered in
seemingly simple assembly routines. This means that some
callers needed to save/restore extra registers.
- The stack pointer must have space for a 'fake' return address
in idle, to avoid stack underflow.
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).
Work done by BSDI, Jonathan Lemon <jlemon@americantv.com>,
Mike Smith <msmith@gsoft.com.au>, Sean Eric Fagan <sef@kithrup.com>,
and probably alot of others.
Submitted by: Jnathan Lemon <jlemon@americantv.com>
- s_lock_init()
- s_lock()
- s_lock_try()
- s_unlock()
Created lock for IO APIC and apic_imen (SMP version of imen)
- imen_lock
Code to use imen_lock for access from apic_ipl.s and apic_vector.s.
Moved this code *outside* of mp_lock.
It seems to work!!!
that lkm's can use them for fiddling the masks without being dependent on
which mode the kernel is compiled in (SMP or UP). This is particularly
for ppp_tty.c which has some domain crossing between the net and tty
subsystems. The values are not used in the spl code, they are for
reference only (ie: the compiled code uses immediate values rather than
an indirect 32 bit address and 32 bit data fetch).
- vector.s <- stub called by i386/exception.s
- icu_vector.s <- UP
- apic_vector.s <- SMP
Split icu.s into UP and SMP specific files:
- ipl.s <- stub called by i386/exception.s (formerly icu.s)
- icu_ipl.s <- UP
- apic_ipl.s <- SMP
This was done in preparation for massive changes to the SMP INTerrupt
mechanisms. More fine tuning, such as merging ipl.s into exception.s,
may be appropriate.
