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- Optimize the amd64 cpu_switch() TD_LOCK blocking and releasing to

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require fewer blocking loops.
 - Don't use atomic ops with 4BSD or on UP.
 - Only use the blocking loop if ULE is compiled in.
 - Use the correct memory barrier.

Discussed with:	attilio, jhb, ssouhlal
Tested by:	current@
Approved by:	re
This commit is contained in:
jeff 2007-07-17 22:36:56 +00:00
parent 3bab343460
commit 8216f30e97
1 changed files with 19 additions and 15 deletions
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34
sys/amd64/amd64/cpu_switch.S
View File

@ -37,6 +37,7 @@
#include <machine/specialreg.h>
#include "assym.s"
#include "opt_sched.h"
/*****************************************************************************/
/* Scheduling */
@ -50,6 +51,12 @@
#define LK
#endif
#if defined(SCHED_ULE) && defined(SMP)
#define SETLK xchgq
#else
#define SETLK movq
#endif
/*
* cpu_throw()
*
@ -148,13 +155,7 @@ ENTRY(cpu_switch)
movq %cr3,%rax
cmpq %rcx,%rax /* Same address space? */
jne swinact
movq %rdx, TD_LOCK(%rdi) /* Release the old thread */
/* Wait for the new thread to become unblocked */
movq $blocked_lock, %rdx
1:
movq TD_LOCK(%rsi),%rcx
cmpq %rcx, %rdx
je 1b
SETLK %rdx, TD_LOCK(%rdi) /* Release the old thread */
jmp sw1
swinact:
movq %rcx,%cr3 /* new address space */
@ -163,21 +164,24 @@ swinact:
movq TD_PROC(%rdi), %rcx /* oldproc */
movq P_VMSPACE(%rcx), %rcx
LK btrl %eax, VM_PMAP+PM_ACTIVE(%rcx) /* clear old */
movq %rdx, TD_LOCK(%rdi) /* Release the old thread */
SETLK %rdx, TD_LOCK(%rdi) /* Release the old thread */
swact:
/* Wait for the new thread to become unblocked */
movq $blocked_lock, %rdx
1:
movq TD_LOCK(%rsi),%rcx
cmpq %rcx, %rdx
je 1b
/* Set bit in new pmap->pm_active */
movq TD_PROC(%rsi),%rdx /* newproc */
movq P_VMSPACE(%rdx), %rdx
LK btsl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */
sw1:
#if defined(SCHED_ULE) && defined(SMP)
/* Wait for the new thread to become unblocked */
movq $blocked_lock, %rdx
1:
movq TD_LOCK(%rsi),%rcx
cmpq %rcx, %rdx
pause
je 1b
lfence
#endif
/*
* At this point, we've switched address spaces and are ready
* to load up the rest of the next context.