From: Dave McCracken It occurred to me that a simple way to improve objrmap performance would be to sort the vma chains off address_space by offset. Here's a patch that does it. Tests show no measureable cost, and it could significantly reduce the impact of the worst case scenario (100 mappings * 100 processes) we've all worried about. 25-akpm/mm/mmap.c | 16 ++++++++++++++-- 1 files changed, 14 insertions(+), 2 deletions(-) diff -puN mm/mmap.c~objrmap-sort-vma-list mm/mmap.c --- 25/mm/mmap.c~objrmap-sort-vma-list Wed Apr 2 13:32:18 2003 +++ 25-akpm/mm/mmap.c Wed Apr 2 13:32:18 2003 @@ -311,14 +311,26 @@ static inline void __vma_link_file(struc if (file) { struct inode * inode = file->f_dentry->d_inode; struct address_space *mapping = inode->i_mapping; + struct list_head *vmlist, *vmhead; if (vma->vm_flags & VM_DENYWRITE) atomic_dec(&inode->i_writecount); if (vma->vm_flags & VM_SHARED) - list_add_tail(&vma->shared, &mapping->i_mmap_shared); + vmhead = &mapping->i_mmap_shared; else - list_add_tail(&vma->shared, &mapping->i_mmap); + vmhead = &mapping->i_mmap; + + list_for_each(vmlist, &mapping->i_mmap_shared) { + struct vm_area_struct *vmtemp; + vmtemp = list_entry(vmlist, struct vm_area_struct, shared); + if (vmtemp->vm_pgoff >= vma->vm_pgoff) + break; + } + if (vmlist == vmhead) + list_add_tail(&vma->shared, vmlist); + else + list_add(&vma->shared, vmlist); } } _