[PATCH] Avoiding mmap fragmentation

[pandora-kernel.git] / arch / i386 / mm / hugetlbpage.c

diff --git a/arch/i386/mm/hugetlbpage.c b/arch/i386/mm/hugetlbpage.c
index 5aa0600..3b099f3 100644 (file)
--- a/arch/i386/mm/hugetlbpage.c
+++ b/arch/i386/mm/hugetlbpage.c
@@ -140,7 +140,12 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
        struct vm_area_struct *vma;
        unsigned long start_addr;
 
-       start_addr = mm->free_area_cache;
+       if (len > mm->cached_hole_size) {
+               start_addr = mm->free_area_cache;
+       } else {
+               start_addr = TASK_UNMAPPED_BASE;
+               mm->cached_hole_size = 0;
+       }
 
 full_search:
        addr = ALIGN(start_addr, HPAGE_SIZE);
@@ -154,6 +159,7 @@ full_search:
                         */
                        if (start_addr != TASK_UNMAPPED_BASE) {
                                start_addr = TASK_UNMAPPED_BASE;
+                               mm->cached_hole_size = 0;
                                goto full_search;
                        }
                        return -ENOMEM;
@@ -162,6 +168,8 @@ full_search:
                        mm->free_area_cache = addr + len;
                        return addr;
                }
+               if (addr + mm->cached_hole_size < vma->vm_start)
+                       mm->cached_hole_size = vma->vm_start - addr;
                addr = ALIGN(vma->vm_end, HPAGE_SIZE);
        }
 }
@@ -173,12 +181,17 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma, *prev_vma;
        unsigned long base = mm->mmap_base, addr = addr0;
+       unsigned long largest_hole = mm->cached_hole_size;
        int first_time = 1;
 
        /* don't allow allocations above current base */
        if (mm->free_area_cache > base)
                mm->free_area_cache = base;
 
+       if (len <= largest_hole) {
+               largest_hole = 0;
+               mm->free_area_cache  = base;
+       }
 try_again:
        /* make sure it can fit in the remaining address space */
        if (mm->free_area_cache < len)
@@ -199,13 +212,21 @@ try_again:
                 * vma->vm_start, use it:
                 */
                if (addr + len <= vma->vm_start &&
-                               (!prev_vma || (addr >= prev_vma->vm_end)))
+                           (!prev_vma || (addr >= prev_vma->vm_end))) {
                        /* remember the address as a hint for next time */
-                       return (mm->free_area_cache = addr);
-               else
+                       mm->cached_hole_size = largest_hole;
+                       return (mm->free_area_cache = addr);
+               } else {
                        /* pull free_area_cache down to the first hole */
-                       if (mm->free_area_cache == vma->vm_end)
+                       if (mm->free_area_cache == vma->vm_end) {
                                mm->free_area_cache = vma->vm_start;
+                               mm->cached_hole_size = largest_hole;
+                       }
+               }
+
+               /* remember the largest hole we saw so far */
+               if (addr + largest_hole < vma->vm_start)
+                       largest_hole = vma->vm_start - addr;
 
                /* try just below the current vma->vm_start */
                addr = (vma->vm_start - len) & HPAGE_MASK;
@@ -218,6 +239,7 @@ fail:
         */
        if (first_time) {
                mm->free_area_cache = base;
+               largest_hole = 0;
                first_time = 0;
                goto try_again;
        }
@@ -228,6 +250,7 @@ fail:
         * allocations.
         */
        mm->free_area_cache = TASK_UNMAPPED_BASE;
+       mm->cached_hole_size = ~0UL;
        addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
                        len, pgoff, flags);
 
@@ -235,6 +258,7 @@ fail:
         * Restore the topdown base:
         */
        mm->free_area_cache = base;
+       mm->cached_hole_size = ~0UL;
 
        return addr;
 }