Date: Tue, 03 Dec 1996 15:08:32 -0600 From: Chris Csanady <ccsanady@friley216.res.iastate.edu> Cc: freebsd-smp@freebsd.org Subject: Finished locks.. Message-ID: <199612032108.PAA15610@friley216.res.iastate.edu> In-Reply-To: Your message of Tue, 03 Dec 1996 00:54:40 -0600. <199612030654.AAA12221@friley216.res.iastate.edu>
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For what it's worth, I have completed a simple implementation of spin
locks. (However, I'm sure someone will tell me different.. :) Either
way, it was nice to learn a bit of assembly.
If these are not sufficient, how can I improve upon them? I'd like to
move some of the locking around, and they would help. In particular, I
am planning to move the global lock out into the syscalls, and perhaps
create a seperate lock for the run queues and such. Then from there, we
can we can reduce the graininess a bit. :)
Anyway, I'd just like to thank all of you for helping me out.
Chris
.text
/***********************************************************************
* void LOCK()
* -----------------
* All registers preserved
*/
.align 2,0x90
.globl _LOCK
_LOCK:
pushl %eax
pushl %ecx
pushl %edx
movl $_smp_active, %eax
cmpl $0, %eax
je 4f
1: movl 16(%esp), %edx
movl $1, %ecx
movl $0, %eax
2: lock
cmpxchg %ecx, (%edx)
jne 3f
jmp 4f
3: cmpl %ecx, (%edx)
je 3b
jmp 2b
4: popl %edx
popl %ecx
popl %eax
ret
/***********************************************************************
* int TRY_LOCK()
* -----------------
* reg %eax == 1 if success
*/
.align 2,0x90
.globl _TRY_LOCK
_TRY_LOCK:
pushl %ecx
pushl %edx
movl $_smp_active, %eax
cmpl $0, %eax
je 1f
movl 12(%esp), %edx
movl $1, %ecx
movl $0, %eax
lock
cmpxchg %ecx, (%edx)
jne 1f
movl $1, %eax
jmp 2f
1: movl $0, %eax
2: popl %edx
popl %ecx
ret
/***********************************************************************
* void UNLOCK()
* -----------------
* All registers preserved
*/
.align 2,0x90
.globl _UNLOCK
_UNLOCK:
pushl %ecx
movl 8(%esp), %ecx
movl $0, (%ecx)
popl %ecx
ret
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