[PATCH] Avoiding mmap fragmentation

[linux-2.6] / arch / ppc64 / mm / hugetlbpage.c

diff --git a/arch/ppc64/mm/hugetlbpage.c b/arch/ppc64/mm/hugetlbpage.c
index b4ab766f59800bcc66774d6ff70c2accc390f835..fdcfe97c75c1dbc388cec0fe261ce446e82ab3e3 100644 (file)
--- a/arch/ppc64/mm/hugetlbpage.c
+++ b/arch/ppc64/mm/hugetlbpage.c
@@ -292,7 +292,12 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
                    && !is_hugepage_only_range(mm, addr,len))
                        return addr;
        }
-       start_addr = addr = mm->free_area_cache;
+       if (len > mm->cached_hole_size) {
+               start_addr = addr = mm->free_area_cache;
+       } else {
+               start_addr = addr = TASK_UNMAPPED_BASE;
+               mm->cached_hole_size = 0;
+       }
 
 full_search:
        vma = find_vma(mm, addr);
@@ -316,6 +321,8 @@ 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 = vma->vm_end;
                vma = vma->vm_next;
        }
@@ -323,6 +330,7 @@ full_search:
        /* Make sure we didn't miss any holes */
        if (start_addr != TASK_UNMAPPED_BASE) {
                start_addr = addr = TASK_UNMAPPED_BASE;
+               mm->cached_hole_size = 0;
                goto full_search;
        }
        return -ENOMEM;
@@ -344,6 +352,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
        struct vm_area_struct *vma, *prev_vma;
        struct mm_struct *mm = current->mm;
        unsigned long base = mm->mmap_base, addr = addr0;
+       unsigned long largest_hole = mm->cached_hole_size;
        int first_time = 1;
 
        /* requested length too big for entire address space */
@@ -364,6 +373,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                        return addr;
        }
 
+       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)
@@ -392,13 +405,21 @@ hugepage_recheck:
                 * 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;
@@ -411,6 +432,7 @@ fail:
         */
        if (first_time) {
                mm->free_area_cache = base;
+               largest_hole = 0;
                first_time = 0;
                goto try_again;
        }
@@ -421,11 +443,13 @@ fail:
         * allocations.
         */
        mm->free_area_cache = TASK_UNMAPPED_BASE;
+       mm->cached_hole_size = ~0UL;
        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
        /*
         * Restore the topdown base:
         */
        mm->free_area_cache = base;
+       mm->cached_hole_size = ~0UL;
 
        return addr;
 }