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Index: sys/vm/vm_fault.c
===================================================================
--- sys/vm/vm_fault.c
+++ sys/vm/vm_fault.c
@@ -681,6 +681,59 @@
return (KERN_RESOURCE_SHORTAGE);
}
+/*
+ * Calculate the desired readahead. Handle drop-behind.
+ *
+ * Returns the number of readahead blocks to pass to the pager.
+ */
+static int
+vm_fault_readahead(struct faultstate *fs)
+{
+ int era, nera;
+ u_char behavior;
+
+ KASSERT(fs->lookup_still_valid, ("map unlocked"));
+ era = fs->entry->read_ahead;
+ behavior = vm_map_entry_behavior(fs->entry);
+ if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
+ nera = 0;
+ } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
+ nera = VM_FAULT_READ_AHEAD_MAX;
+ if (fs->vaddr == fs->entry->next_read)
+ vm_fault_dontneed(fs, fs->vaddr, nera);
+ } else if (fs->vaddr == fs->entry->next_read) {
+ /*
+ * This is a sequential fault. Arithmetically
+ * increase the requested number of pages in
+ * the read-ahead window. The requested
+ * number of pages is "# of sequential faults
+ * x (read ahead min + 1) + read ahead min"
+ */
+ nera = VM_FAULT_READ_AHEAD_MIN;
+ if (era > 0) {
+ nera += era + 1;
+ if (nera > VM_FAULT_READ_AHEAD_MAX)
+ nera = VM_FAULT_READ_AHEAD_MAX;
+ }
+ if (era == VM_FAULT_READ_AHEAD_MAX)
+ vm_fault_dontneed(fs, fs->vaddr, nera);
+ } else {
+ /*
+ * This is a non-sequential fault.
+ */
+ nera = 0;
+ }
+ if (era != nera) {
+ /*
+ * A read lock on the map suffices to update
+ * the read ahead count safely.
+ */
+ fs->entry->read_ahead = nera;
+ }
+
+ return (nera);
+}
+
/*
* Wait/Retry if the page is busy. We have to do this if the page is
* either exclusive or shared busy because the vm_pager may be using
@@ -727,7 +780,7 @@
vm_offset_t e_end, e_start;
vm_pindex_t retry_pindex;
vm_prot_t prot, retry_prot;
- int ahead, alloc_req, behind, cluster_offset, era, faultcount;
+ int ahead, alloc_req, behind, cluster_offset, faultcount;
int nera, oom, result, rv;
u_char behavior;
boolean_t wired; /* Passed by reference. */
@@ -991,45 +1044,7 @@
* apply to subsequent objects in the shadow chain.
*/
if (nera == -1 && !P_KILLED(curproc)) {
- KASSERT(fs.lookup_still_valid, ("map unlocked"));
- era = fs.entry->read_ahead;
- behavior = vm_map_entry_behavior(fs.entry);
- if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
- nera = 0;
- } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
- nera = VM_FAULT_READ_AHEAD_MAX;
- if (vaddr == fs.entry->next_read)
- vm_fault_dontneed(&fs, vaddr, nera);
- } else if (vaddr == fs.entry->next_read) {
- /*
- * This is a sequential fault. Arithmetically
- * increase the requested number of pages in
- * the read-ahead window. The requested
- * number of pages is "# of sequential faults
- * x (read ahead min + 1) + read ahead min"
- */
- nera = VM_FAULT_READ_AHEAD_MIN;
- if (era > 0) {
- nera += era + 1;
- if (nera > VM_FAULT_READ_AHEAD_MAX)
- nera = VM_FAULT_READ_AHEAD_MAX;
- }
- if (era == VM_FAULT_READ_AHEAD_MAX)
- vm_fault_dontneed(&fs, vaddr, nera);
- } else {
- /*
- * This is a non-sequential fault.
- */
- nera = 0;
- }
- if (era != nera) {
- /*
- * A read lock on the map suffices to update
- * the read ahead count safely.
- */
- fs.entry->read_ahead = nera;
- }
-
+ nera = vm_fault_readahead(&fs);
/*
* Prepare for unlocking the map. Save the map
* entry's start and end addresses, which are used to
@@ -1040,6 +1055,7 @@
*/
e_start = fs.entry->start;
e_end = fs.entry->end;
+ behavior = vm_map_entry_behavior(fs.entry);
}
/*

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