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Date:      Wed, 9 Jul 2014 08:12:59 +0000 (UTC)
From:      Roger Pau Monné <royger@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r268451 - head/sys/vm
Message-ID:  <201407090812.s698Cxsk057882@svn.freebsd.org>

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Author: royger
Date: Wed Jul  9 08:12:58 2014
New Revision: 268451
URL: http://svnweb.freebsd.org/changeset/base/268451

Log:
  vm_phys: remove limitation on number of fictitious regions
  
  The number of vm fictitious regions was limited to 8 by default, but
  Xen will make heavy usage of those kind of regions in order to map
  memory from foreign domains, so instead of increasing the default
  number, change the implementation to use a red-black tree to track vm
  fictitious ranges.
  
  The public interface remains the same.
  
  Sponsored by: Citrix Systems R&D
  Reviewed by: kib, alc
  Approved by: gibbs
  
  vm/vm_phys.c:
   - Replace the vm fictitious static array with a red-black tree.
   - Use a rwlock instead of a mutex, since now we also need to take the
     lock in vm_phys_fictitious_to_vm_page, and it can be shared.

Modified:
  head/sys/vm/vm_phys.c

Modified: head/sys/vm/vm_phys.c
==============================================================================
--- head/sys/vm/vm_phys.c	Wed Jul  9 07:48:05 2014	(r268450)
+++ head/sys/vm/vm_phys.c	Wed Jul  9 08:12:58 2014	(r268451)
@@ -52,8 +52,10 @@ __FBSDID("$FreeBSD$");
 #include <sys/proc.h>
 #endif
 #include <sys/queue.h>
+#include <sys/rwlock.h>
 #include <sys/sbuf.h>
 #include <sys/sysctl.h>
+#include <sys/tree.h>
 #include <sys/vmmeter.h>
 
 #include <ddb/ddb.h>
@@ -75,13 +77,25 @@ int vm_ndomains = 1;
 struct vm_phys_seg vm_phys_segs[VM_PHYSSEG_MAX];
 int vm_phys_nsegs;
 
-#define VM_PHYS_FICTITIOUS_NSEGS	8
-static struct vm_phys_fictitious_seg {
+struct vm_phys_fictitious_seg;
+static int vm_phys_fictitious_cmp(struct vm_phys_fictitious_seg *,
+    struct vm_phys_fictitious_seg *);
+
+RB_HEAD(fict_tree, vm_phys_fictitious_seg) vm_phys_fictitious_tree =
+    RB_INITIALIZER(_vm_phys_fictitious_tree);
+
+struct vm_phys_fictitious_seg {
+	RB_ENTRY(vm_phys_fictitious_seg) node;
+	/* Memory region data */
 	vm_paddr_t	start;
 	vm_paddr_t	end;
 	vm_page_t	first_page;
-} vm_phys_fictitious_segs[VM_PHYS_FICTITIOUS_NSEGS];
-static struct mtx vm_phys_fictitious_reg_mtx;
+};
+
+RB_GENERATE_STATIC(fict_tree, vm_phys_fictitious_seg, node,
+    vm_phys_fictitious_cmp);
+
+static struct rwlock vm_phys_fictitious_reg_lock;
 MALLOC_DEFINE(M_FICT_PAGES, "vm_fictitious", "Fictitious VM pages");
 
 static struct vm_freelist
@@ -113,6 +127,47 @@ static int vm_phys_paddr_to_segind(vm_pa
 static void vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl,
     int order);
 
+/*
+ * Red-black tree helpers for vm fictitious range management.
+ */
+static inline int
+vm_phys_fictitious_in_range(struct vm_phys_fictitious_seg *p,
+    struct vm_phys_fictitious_seg *range)
+{
+
+	KASSERT(range->start != 0 && range->end != 0,
+	    ("Invalid range passed on search for vm_fictitious page"));
+	if (p->start >= range->end)
+		return (1);
+	if (p->start < range->start)
+		return (-1);
+
+	return (0);
+}
+
+static int
+vm_phys_fictitious_cmp(struct vm_phys_fictitious_seg *p1,
+    struct vm_phys_fictitious_seg *p2)
+{
+
+	/* Check if this is a search for a page */
+	if (p1->end == 0)
+		return (vm_phys_fictitious_in_range(p1, p2));
+
+	KASSERT(p2->end != 0,
+    ("Invalid range passed as second parameter to vm fictitious comparison"));
+
+	/* Searching to add a new range */
+	if (p1->end <= p2->start)
+		return (-1);
+	if (p1->start >= p2->end)
+		return (1);
+
+	panic("Trying to add overlapping vm fictitious ranges:\n"
+	    "[%#jx:%#jx] and [%#jx:%#jx]", (uintmax_t)p1->start,
+	    (uintmax_t)p1->end, (uintmax_t)p2->start, (uintmax_t)p2->end);
+}
+
 static __inline int
 vm_rr_selectdomain(void)
 {
@@ -353,7 +408,7 @@ vm_phys_init(void)
 			}
 		}
 	}
-	mtx_init(&vm_phys_fictitious_reg_mtx, "vmfctr", NULL, MTX_DEF);
+	rw_init(&vm_phys_fictitious_reg_lock, "vmfctr");
 }
 
 /*
@@ -517,20 +572,22 @@ vm_phys_paddr_to_vm_page(vm_paddr_t pa)
 vm_page_t
 vm_phys_fictitious_to_vm_page(vm_paddr_t pa)
 {
-	struct vm_phys_fictitious_seg *seg;
+	struct vm_phys_fictitious_seg tmp, *seg;
 	vm_page_t m;
-	int segind;
 
 	m = NULL;
-	for (segind = 0; segind < VM_PHYS_FICTITIOUS_NSEGS; segind++) {
-		seg = &vm_phys_fictitious_segs[segind];
-		if (pa >= seg->start && pa < seg->end) {
-			m = &seg->first_page[atop(pa - seg->start)];
-			KASSERT((m->flags & PG_FICTITIOUS) != 0,
-			    ("%p not fictitious", m));
-			break;
-		}
-	}
+	tmp.start = pa;
+	tmp.end = 0;
+
+	rw_rlock(&vm_phys_fictitious_reg_lock);
+	seg = RB_FIND(fict_tree, &vm_phys_fictitious_tree, &tmp);
+	rw_runlock(&vm_phys_fictitious_reg_lock);
+	if (seg == NULL)
+		return (NULL);
+
+	m = &seg->first_page[atop(pa - seg->start)];
+	KASSERT((m->flags & PG_FICTITIOUS) != 0, ("%p not fictitious", m));
+
 	return (m);
 }
 
@@ -541,10 +598,8 @@ vm_phys_fictitious_reg_range(vm_paddr_t 
 	struct vm_phys_fictitious_seg *seg;
 	vm_page_t fp;
 	long i, page_count;
-	int segind;
 #ifdef VM_PHYSSEG_DENSE
 	long pi;
-	boolean_t malloced;
 #endif
 
 	page_count = (end - start) / PAGE_SIZE;
@@ -555,46 +610,34 @@ vm_phys_fictitious_reg_range(vm_paddr_t 
 		if (atop(end) >= vm_page_array_size + first_page)
 			return (EINVAL);
 		fp = &vm_page_array[pi - first_page];
-		malloced = FALSE;
 	} else
 #endif
 	{
 		fp = malloc(page_count * sizeof(struct vm_page), M_FICT_PAGES,
 		    M_WAITOK | M_ZERO);
-#ifdef VM_PHYSSEG_DENSE
-		malloced = TRUE;
-#endif
 	}
 	for (i = 0; i < page_count; i++) {
 		vm_page_initfake(&fp[i], start + PAGE_SIZE * i, memattr);
 		fp[i].oflags &= ~VPO_UNMANAGED;
 		fp[i].busy_lock = VPB_UNBUSIED;
 	}
-	mtx_lock(&vm_phys_fictitious_reg_mtx);
-	for (segind = 0; segind < VM_PHYS_FICTITIOUS_NSEGS; segind++) {
-		seg = &vm_phys_fictitious_segs[segind];
-		if (seg->start == 0 && seg->end == 0) {
-			seg->start = start;
-			seg->end = end;
-			seg->first_page = fp;
-			mtx_unlock(&vm_phys_fictitious_reg_mtx);
-			return (0);
-		}
-	}
-	mtx_unlock(&vm_phys_fictitious_reg_mtx);
-#ifdef VM_PHYSSEG_DENSE
-	if (malloced)
-#endif
-		free(fp, M_FICT_PAGES);
-	return (EBUSY);
+
+	seg = malloc(sizeof(*seg), M_FICT_PAGES, M_WAITOK | M_ZERO);
+	seg->start = start;
+	seg->end = end;
+	seg->first_page = fp;
+
+	rw_wlock(&vm_phys_fictitious_reg_lock);
+	RB_INSERT(fict_tree, &vm_phys_fictitious_tree, seg);
+	rw_wunlock(&vm_phys_fictitious_reg_lock);
+
+	return (0);
 }
 
 void
 vm_phys_fictitious_unreg_range(vm_paddr_t start, vm_paddr_t end)
 {
-	struct vm_phys_fictitious_seg *seg;
-	vm_page_t fp;
-	int segind;
+	struct vm_phys_fictitious_seg *seg, tmp;
 #ifdef VM_PHYSSEG_DENSE
 	long pi;
 #endif
@@ -602,24 +645,24 @@ vm_phys_fictitious_unreg_range(vm_paddr_
 #ifdef VM_PHYSSEG_DENSE
 	pi = atop(start);
 #endif
+	tmp.start = start;
+	tmp.end = 0;
 
-	mtx_lock(&vm_phys_fictitious_reg_mtx);
-	for (segind = 0; segind < VM_PHYS_FICTITIOUS_NSEGS; segind++) {
-		seg = &vm_phys_fictitious_segs[segind];
-		if (seg->start == start && seg->end == end) {
-			seg->start = seg->end = 0;
-			fp = seg->first_page;
-			seg->first_page = NULL;
-			mtx_unlock(&vm_phys_fictitious_reg_mtx);
+	rw_wlock(&vm_phys_fictitious_reg_lock);
+	seg = RB_FIND(fict_tree, &vm_phys_fictitious_tree, &tmp);
+	if (seg->start != start || seg->end != end) {
+		rw_wunlock(&vm_phys_fictitious_reg_lock);
+		panic(
+		    "Unregistering not registered fictitious range [%#jx:%#jx]",
+		    (uintmax_t)start, (uintmax_t)end);
+	}
+	RB_REMOVE(fict_tree, &vm_phys_fictitious_tree, seg);
+	rw_wunlock(&vm_phys_fictitious_reg_lock);
 #ifdef VM_PHYSSEG_DENSE
-			if (pi < first_page || atop(end) >= vm_page_array_size)
+	if (pi < first_page || atop(end) >= vm_page_array_size)
 #endif
-				free(fp, M_FICT_PAGES);
-			return;
-		}
-	}
-	mtx_unlock(&vm_phys_fictitious_reg_mtx);
-	KASSERT(0, ("Unregistering not registered fictitious range"));
+		free(seg->first_page, M_FICT_PAGES);
+	free(seg, M_FICT_PAGES);
 }
 
 /*



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