vm_phys: add binary segment search

Replace several sequential searches for a segment that contains a
phyiscal address with a call to a function that does it by binary
search.  In vm_page_reclaim_contig_domain_ext, find the first segment
to reclaim from, and reclaim from each subsequent appropriate segment.
Eliminate vm_phys_scan_contig.

Reviewed by:	alc, markj
Differential Revision:	https://reviews.freebsd.org/D40058

sys/arm64/arm64/pmap.c

@@ -210,14 +210,10 @@ static struct pmap_large_md_page *
 _pa_to_pmdp(vm_paddr_t pa)
 {
 	struct vm_phys_seg *seg;
-	int segind;
 
-	for (segind = 0; segind < vm_phys_nsegs; segind++) {
-		seg = &vm_phys_segs[segind];
-		if (pa >= seg->start && pa < seg->end)
-			return ((struct pmap_large_md_page *)seg->md_first +
-			    pmap_l2_pindex(pa) - pmap_l2_pindex(seg->start));
-	}
+	if ((seg = vm_phys_paddr_to_seg(pa)) != NULL)
+		return ((struct pmap_large_md_page *)seg->md_first +
+		    pmap_l2_pindex(pa) - pmap_l2_pindex(seg->start));
 	return (NULL);
 }
 

sys/vm/vm_page.c

@@ -2627,7 +2627,7 @@ vm_page_zone_release(void *arg, void **store, int cnt)
  *	span a hole (or discontiguity) in the physical address space.  Both
  *	"alignment" and "boundary" must be a power of two.
  */
-vm_page_t
+static vm_page_t
 vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
     u_long alignment, vm_paddr_t boundary, int options)
 {
@@ -3028,10 +3028,9 @@ vm_page_reclaim_contig_domain_ext(int domain, int req, u_long npages,
     int desired_runs)
 {
 	struct vm_domain *vmd;
-	vm_paddr_t curr_low;
-	vm_page_t m_run, _m_runs[NRUNS], *m_runs;
+	vm_page_t bounds[2], m_run, _m_runs[NRUNS], *m_runs;
 	u_long count, minalign, reclaimed;
-	int error, i, min_reclaim, nruns, options, req_class;
+	int error, i, min_reclaim, nruns, options, req_class, segind;
 	bool ret;
 
 	KASSERT(npages > 0, ("npages is 0"));
@@ -3098,16 +3097,17 @@ vm_page_reclaim_contig_domain_ext(int domain, int req, u_long npages,
 		 * Find the highest runs that satisfy the given constraints
 		 * and restrictions, and record them in "m_runs".
 		 */
-		curr_low = low;
 		count = 0;
-		for (;;) {
-			m_run = vm_phys_scan_contig(domain, npages, curr_low,
-			    high, alignment, boundary, options);
-			if (m_run == NULL)
-				break;
-			curr_low = VM_PAGE_TO_PHYS(m_run) + ptoa(npages);
-			m_runs[RUN_INDEX(count, nruns)] = m_run;
-			count++;
+		segind = vm_phys_lookup_segind(low);
+		while ((segind = vm_phys_find_range(bounds, segind, domain,
+		    npages, low, high)) != -1) {
+			while ((m_run = vm_page_scan_contig(npages, bounds[0],
+			    bounds[1], alignment, boundary, options))) {
+				bounds[0] = m_run + npages;
+				m_runs[RUN_INDEX(count, nruns)] = m_run;
+				count++;
+			}
+			segind++;
 		}
 
 		/*

sys/vm/vm_page.h

@@ -683,8 +683,6 @@ int vm_page_rename(vm_page_t, vm_object_t, vm_pindex_t);
 void vm_page_replace(vm_page_t mnew, vm_object_t object,
     vm_pindex_t pindex, vm_page_t mold);
 int vm_page_sbusied(vm_page_t m);
-vm_page_t vm_page_scan_contig(u_long npages, vm_page_t m_start,
-    vm_page_t m_end, u_long alignment, vm_paddr_t boundary, int options);
 vm_page_bits_t vm_page_set_dirty(vm_page_t m);
 void vm_page_set_valid_range(vm_page_t m, int base, int size);
 vm_offset_t vm_page_startup(vm_offset_t vaddr);

sys/vm/vm_phys.c

@@ -898,13 +898,9 @@ vm_page_t
 vm_phys_paddr_to_vm_page(vm_paddr_t pa)
 {
 	struct vm_phys_seg *seg;
-	int segind;
 
-	for (segind = 0; segind < vm_phys_nsegs; segind++) {
-		seg = &vm_phys_segs[segind];
-		if (pa >= seg->start && pa < seg->end)
-			return (&seg->first_page[atop(pa - seg->start)]);
-	}
+	if ((seg = vm_phys_paddr_to_seg(pa)) != NULL)
+		return (&seg->first_page[atop(pa - seg->start)]);
 	return (NULL);
 }
 
@@ -1238,55 +1234,34 @@ vm_phys_free_contig(vm_page_t m, u_long npages)
 }
 
 /*
- * Scan physical memory between the specified addresses "low" and "high" for a
- * run of contiguous physical pages that satisfy the specified conditions, and
- * return the lowest page in the run.  The specified "alignment" determines
- * the alignment of the lowest physical page in the run.  If the specified
- * "boundary" is non-zero, then the run of physical pages cannot span a
- * physical address that is a multiple of "boundary".
- *
- * "npages" must be greater than zero.  Both "alignment" and "boundary" must
- * be a power of two.
+ * Identify the first address range within segment segind or greater
+ * that matches the domain, lies within the low/high range, and has
+ * enough pages.  Return -1 if there is none.
  */
-vm_page_t
-vm_phys_scan_contig(int domain, u_long npages, vm_paddr_t low, vm_paddr_t high,
-    u_long alignment, vm_paddr_t boundary, int options)
+int
+vm_phys_find_range(vm_page_t bounds[], int segind, int domain,
+    u_long npages, vm_paddr_t low, vm_paddr_t high)
 {
-	vm_paddr_t pa_end;
-	vm_page_t m_end, m_run, m_start;
-	struct vm_phys_seg *seg;
-	int segind;
+	vm_paddr_t pa_end, pa_start;
+	struct vm_phys_seg *end_seg, *seg;
 
-	KASSERT(npages > 0, ("npages is 0"));
-	KASSERT(powerof2(alignment), ("alignment is not a power of 2"));
-	KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
-	if (low >= high)
-		return (NULL);
-	for (segind = 0; segind < vm_phys_nsegs; segind++) {
-		seg = &vm_phys_segs[segind];
+	KASSERT(npages > 0, ("npages is zero"));
+	KASSERT(domain >= 0 && domain < vm_ndomain, ("domain out of range"));
+	end_seg = &vm_phys_segs[vm_phys_nsegs];
+	for (seg = &vm_phys_segs[segind]; seg < end_seg; seg++) {
 		if (seg->domain != domain)
 			continue;
 		if (seg->start >= high)
-			break;
-		if (low >= seg->end)
-			continue;
-		if (low <= seg->start)
-			m_start = seg->first_page;
-		else
-			m_start = &seg->first_page[atop(low - seg->start)];
-		if (high < seg->end)
-			pa_end = high;
-		else
-			pa_end = seg->end;
-		if (pa_end - VM_PAGE_TO_PHYS(m_start) < ptoa(npages))
+			return (-1);
+		pa_start = MAX(low, seg->start);
+		pa_end = MIN(high, seg->end);
+		if (pa_end - pa_start < ptoa(npages))
 			continue;
-		m_end = &seg->first_page[atop(pa_end - seg->start)];
-		m_run = vm_page_scan_contig(npages, m_start, m_end,
-		    alignment, boundary, options);
-		if (m_run != NULL)
-			return (m_run);
+		bounds[0] = &seg->first_page[atop(pa_start - seg->start)];
+		bounds[1] = &seg->first_page[atop(pa_end - seg->start)];
+		return (seg - vm_phys_segs);
 	}
-	return (NULL);
+	return (-1);
 }
 
 /*

sys/vm/vm_phys.h

@@ -42,6 +42,8 @@
 
 #ifdef _KERNEL
 
+#include <vm/_vm_phys.h>
+
 extern vm_paddr_t phys_avail[];
 
 /* Domains must be dense (non-sparse) and zero-based. */
@@ -71,14 +73,14 @@ int vm_phys_fictitious_reg_range(vm_paddr_t start, vm_paddr_t end,
     vm_memattr_t memattr);
 void vm_phys_fictitious_unreg_range(vm_paddr_t start, vm_paddr_t end);
 vm_page_t vm_phys_fictitious_to_vm_page(vm_paddr_t pa);
+int vm_phys_find_range(vm_page_t bounds[], int segind, int domain,
+    u_long npages, vm_paddr_t low, vm_paddr_t high);
 void vm_phys_free_contig(vm_page_t m, u_long npages);
 void vm_phys_free_pages(vm_page_t m, int order);
 void vm_phys_init(void);
 vm_page_t vm_phys_paddr_to_vm_page(vm_paddr_t pa);
 void vm_phys_register_domains(int ndomains, struct mem_affinity *affinity,
     int *locality);
-vm_page_t vm_phys_scan_contig(int domain, u_long npages, vm_paddr_t low,
-    vm_paddr_t high, u_long alignment, vm_paddr_t boundary, int options);
 bool vm_phys_unfree_page(vm_page_t m);
 int vm_phys_mem_affinity(int f, int t);
 void vm_phys_early_add_seg(vm_paddr_t start, vm_paddr_t end);
@@ -106,5 +108,47 @@ vm_phys_domain(vm_paddr_t pa)
 #endif
 }
 
+/*
+ * Find the segind for the first segment at or after the given physical address.
+ */
+static inline int
+vm_phys_lookup_segind(vm_paddr_t pa)
+{
+	u_int hi, lo, mid;
+
+	lo = 0;
+	hi = vm_phys_nsegs;
+	while (lo != hi) {
+		/*
+		 * for i in [0, lo), segs[i].end <= pa
+		 * for i in [hi, nsegs), segs[i].end > pa
+		 */
+		mid = lo + (hi - lo) / 2;
+		if (vm_phys_segs[mid].end <= pa)
+			lo = mid + 1;
+		else
+			hi = mid;
+	}
+	return (lo);
+}
+
+/*
+ * Find the segment corresponding to the given physical address.
+ */
+static inline struct vm_phys_seg *
+vm_phys_paddr_to_seg(vm_paddr_t pa)
+{
+	struct vm_phys_seg *seg;
+	int segind;
+
+	segind = vm_phys_lookup_segind(pa);
+	if (segind < vm_phys_nsegs) {
+		seg = &vm_phys_segs[segind];
+		if (pa >= seg->start)
+			return (seg);
+	}
+	return (NULL);
+}
+
 #endif	/* _KERNEL */
 #endif	/* !_VM_PHYS_H_ */