On Alan's advice, rather than do a wholesale conversion on a single

architecture from page queue lock to a hashed array of page locks
(based on a patch by Jeff Roberson), I've implemented page lock
support in the MI code and have only moved vm_page's hold_count
out from under page queue mutex to page lock. This changes
pmap_extract_and_hold on all pmaps.

Supported by: Bitgravity Inc.

Discussed with: alc, jeffr, and kib

2 files changed, 9 insertions, 4 deletions

diff --git a/sys/mips/include/pmap.h b/sys/mips/include/pmap.h
index 80772d9..f4df6ca 100644
--- a/sys/mips/include/pmap.h
+++ b/sys/mips/include/pmap.h
@@ -88,6 +88,8 @@ struct pmap {
 	pd_entry_t *pm_segtab;	/* KVA of segment table */
 	TAILQ_HEAD(, pv_entry) pm_pvlist;	/* list of mappings in
 						 * pmap */
+	uint32_t	pm_gen_count;	/* generation count (pmap lock dropped) */
+	u_int		pm_retries;
 	int pm_active;		/* active on cpus */
 	struct {
 		u_int32_t asid:ASID_BITS;	/* TLB address space tag */
diff --git a/sys/mips/mips/pmap.c b/sys/mips/mips/pmap.c
index e7c3239..826177f 100644
--- a/sys/mips/mips/pmap.c
+++ b/sys/mips/mips/pmap.c
@@ -147,7 +147,6 @@ unsigned pmap_max_asid;		/* max ASID supported by the system */
 
 #define	PMAP_ASID_RESERVED	0
 
-
 vm_offset_t kernel_vm_end;
 
 static struct tlb tlbstash[MAXCPU][MIPS_MAX_TLB_ENTRIES];
@@ -710,18 +709,22 @@ pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
 {
 	pt_entry_t pte;
 	vm_page_t m;
+	vm_paddr_t pa;
 
 	m = NULL;
-	vm_page_lock_queues();
+	pa = 0;
 	PMAP_LOCK(pmap);
-
+retry:
 	pte = *pmap_pte(pmap, va);
 	if (pte != 0 && pmap_pte_v(&pte) &&
 	    ((pte & PTE_RW) || (prot & VM_PROT_WRITE) == 0)) {
+		if (vm_page_pa_tryrelock(pmap, mips_tlbpfn_to_paddr(pte), &pa))
+			goto retry;
+
 		m = PHYS_TO_VM_PAGE(mips_tlbpfn_to_paddr(pte));
 		vm_page_hold(m);
 	}
-	vm_page_unlock_queues();
+	PA_UNLOCK_COND(pa);
 	PMAP_UNLOCK(pmap);
 	return (m);
 }