Diff below remove the KERNEL_LOCK()/UNLOCK() dance from uvm_fault() for
both amd64 and sparc64. That means the kernel lock will only be taken
for lower faults and some amap/anon code will now run without it.
I'd be interested to have this tested and see how much does that impact
the build time of packages.
We should be able to do the switch on an arch-by-arch basis. It's
easier for me to develop & debug on these two architectures so I started
with them. If you want to unlock another architecture and report back,
I'd be glad.
Thanks,
Martin
Index: arch/amd64/amd64/trap.c
===================================================================
RCS file: /cvs/src/sys/arch/amd64/amd64/trap.c,v
retrieving revision 1.87
diff -u -p -r1.87 trap.c
--- arch/amd64/amd64/trap.c 22 Oct 2020 13:41:51 -0000 1.87
+++ arch/amd64/amd64/trap.c 22 Apr 2021 13:06:54 -0000
@@ -176,10 +176,7 @@ upageflttrap(struct trapframe *frame, ui
union sigval sv;
int signal, sicode, error;
- KERNEL_LOCK();
error = uvm_fault(&p->p_vmspace->vm_map, va, 0, access_type);
- KERNEL_UNLOCK();
-
if (error == 0) {
uvm_grow(p, va);
return 1;
@@ -261,9 +258,7 @@ kpageflttrap(struct trapframe *frame, ui
if (curcpu()->ci_inatomic == 0 || map == kernel_map) {
onfault = pcb->pcb_onfault;
pcb->pcb_onfault = NULL;
- KERNEL_LOCK();
error = uvm_fault(map, va, 0, access_type);
- KERNEL_UNLOCK();
pcb->pcb_onfault = onfault;
if (error == 0 && map != kernel_map)
Index: arch/sparc64/sparc64/trap.c
===================================================================
RCS file: /cvs/src/sys/arch/sparc64/sparc64/trap.c,v
retrieving revision 1.108
diff -u -p -r1.108 trap.c
--- arch/sparc64/sparc64/trap.c 11 Mar 2021 11:17:00 -0000 1.108
+++ arch/sparc64/sparc64/trap.c 22 Apr 2021 13:06:54 -0000
@@ -773,10 +773,7 @@ data_access_fault(struct trapframe64 *tf
if (!(addr & TLB_TAG_ACCESS_CTX)) {
/* CTXT == NUCLEUS */
- KERNEL_LOCK();
error = uvm_fault(kernel_map, va, 0, access_type);
- KERNEL_UNLOCK();
-
if (error == 0)
return;
goto kfault;
@@ -792,9 +789,7 @@ data_access_fault(struct trapframe64 *tf
onfault = (vaddr_t)p->p_addr->u_pcb.pcb_onfault;
p->p_addr->u_pcb.pcb_onfault = NULL;
- KERNEL_LOCK();
error = uvm_fault(&p->p_vmspace->vm_map, (vaddr_t)va, 0, access_type);
- KERNEL_UNLOCK();
p->p_addr->u_pcb.pcb_onfault = (void *)onfault;
/*
@@ -959,9 +954,7 @@ text_access_fault(struct trapframe64 *tf
uvm_map_inentry_sp, p->p_vmspace->vm_map.sserial))
goto out;
- KERNEL_LOCK();
error = uvm_fault(&p->p_vmspace->vm_map, va, 0, access_type);
- KERNEL_UNLOCK();
/*
* If this was a stack access we keep track of the maximum
@@ -1055,9 +1048,7 @@ text_access_error(struct trapframe64 *tf
uvm_map_inentry_sp, p->p_vmspace->vm_map.sserial))
goto out;
- KERNEL_LOCK();
error = uvm_fault(&p->p_vmspace->vm_map, va, 0, access_type);
- KERNEL_UNLOCK();
/*
* If this was a stack access we keep track of the maximum
