Add a hack option to update the only local pgmap

c63a4bc8 · Silas Boyd-Wickizer · b94e9aa3 · c63a4bc8
--- a/kernel/vm.cc
+++ b/kernel/vm.cc
@@ -21,6 +21,8 @@
 enum { vm_debug = 0 };
 enum { tlb_shootdown = 1 };
 enum { tlb_lazy = 1 };
+// XXX(sbw) has the same behavior as tlb_shootdown when pgmaps are shared
+enum { never_updateall = 0 };
 /*
 * vmnode
@@ -408,7 +410,7 @@ vmap::insert(vmnode *n, uptr vma_start, int dotlb, proc_pgmap* pgmap)
  vma *e;
  bool replaced = false;
  bool fixed = (vma_start != 0);
-  bool updateall = true;
+  bool updateall = !never_updateall;
 again:
  if (!fixed) {
@@ -503,7 +505,7 @@ again:
    if (needtlb && dotlb)
      tlbflush();
    else
-      if (tlb_lazy)
+      if (tlb_lazy && updateall)
        tlbflush(myproc()->unmap_tlbreq_);
  }
@@ -513,7 +515,7 @@ again:
 int
 vmap::remove(uptr vma_start, uptr len, proc_pgmap* pgmap)
 {
-  bool updateall = true;
+  bool updateall = !never_updateall;
  {
    // new scope to release the search lock before tlbflush