From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Patch avoiding-mmap-fragmentation.patch proposed in 2.6.12-rc4-mm2 tries to
solve a VM address space fragmentation issue for 32-bit app where
free_area_cache algorithm leads to inefficient use of vm address space.
However, the issue is only restricted to 32-bit app. This patch reverse
the unnecessary change made in arch/ia64 and make x86_64 to use the
proposed cache algorithm only for 32-bit app.
Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Cc: Wolfgang Wander <wwc@rentec.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
arch/ia64/kernel/sys_ia64.c | 13 ++-----------
arch/x86_64/kernel/sys_x86_64.c | 2 +-
2 files changed, 3 insertions(+), 12 deletions(-)
diff -puN arch/ia64/kernel/sys_ia64.c~avoiding-mmap-fragmentation-revert-unneeded-64-bit-changes arch/ia64/kernel/sys_ia64.c
--- 25/arch/ia64/kernel/sys_ia64.c~avoiding-mmap-fragmentation-revert-unneeded-64-bit-changes 2005-06-02 22:34:14.000000000 -0700
+++ 25-akpm/arch/ia64/kernel/sys_ia64.c 2005-06-02 22:34:14.000000000 -0700
@@ -38,14 +38,8 @@ arch_get_unmapped_area (struct file *fil
if (REGION_NUMBER(addr) == REGION_HPAGE)
addr = 0;
#endif
- if (!addr) {
- if (len > mm->cached_hole_size) {
- addr = mm->free_area_cache;
- } else {
- addr = TASK_UNMAPPED_BASE;
- mm->cached_hole_size = 0;
- }
- }
+ if (!addr)
+ addr = mm->free_area_cache;
if (map_shared && (TASK_SIZE > 0xfffffffful))
/*
@@ -65,7 +59,6 @@ arch_get_unmapped_area (struct file *fil
if (start_addr != TASK_UNMAPPED_BASE) {
/* Start a new search --- just in case we missed some holes. */
addr = TASK_UNMAPPED_BASE;
- mm->cached_hole_size = 0;
goto full_search;
}
return -ENOMEM;
@@ -75,8 +68,6 @@ arch_get_unmapped_area (struct file *fil
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 + align_mask) & ~align_mask;
}
}
diff -puN arch/x86_64/kernel/sys_x86_64.c~avoiding-mmap-fragmentation-revert-unneeded-64-bit-changes arch/x86_64/kernel/sys_x86_64.c
--- 25/arch/x86_64/kernel/sys_x86_64.c~avoiding-mmap-fragmentation-revert-unneeded-64-bit-changes 2005-06-02 22:34:14.000000000 -0700
+++ 25-akpm/arch/x86_64/kernel/sys_x86_64.c 2005-06-02 22:34:14.000000000 -0700
@@ -105,7 +105,7 @@ arch_get_unmapped_area(struct file *filp
(!vma || addr + len <= vma->vm_start))
return addr;
}
- if (len <= mm->cached_hole_size) {
+ if (begin != TASK_UNMAPPED_64 && len <= mm->cached_hole_size) {
mm->cached_hole_size = 0;
mm->free_area_cache = begin;
}
_