[PATCH 1/2] madvise: do not split the maps
DORMANTno replies
From: <hidden>
Date: 2005-03-16 09:22:07
This attempts to avoid splittings when it is not needed, that is when vm_flags are same as new flags. The idea is from the <2.6.11 mlock_fixup and others. This will provide base for the next madvise merging patch. Signed-off-by: Prasanna Meda <redacted>
--- linux/mm/madvise.c Mon Mar 14 23:46:16 2005
+++ Linux/mm/madvise.c Wed Mar 16 06:17:58 2005@@ -19,6 +19,21 @@ { struct mm_struct * mm = vma->vm_mm; int error = 0; + int new_flags = vma->vm_flags & ~VM_READHINTMASK; + + switch (behavior) { + case MADV_SEQUENTIAL: + new_flags |= VM_SEQ_READ; + break; + case MADV_RANDOM: + new_flags |= VM_RAND_READ; + break; + default: + break; + } + + if (new_flags == vma->vm_flags) + goto out; if (start != vma->vm_start) { error = split_vma(mm, vma, start, 1);
@@ -36,17 +51,7 @@ * vm_flags is protected by the mmap_sem held in write mode. */ VM_ClearReadHint(vma); - - switch (behavior) { - case MADV_SEQUENTIAL: - vma->vm_flags |= VM_SEQ_READ; - break; - case MADV_RANDOM: - vma->vm_flags |= VM_RAND_READ; - break; - default: - break; - } + vma->vm_flags = new_flags; out: if (error == -ENOMEM) --
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"aart@kvack.org"> aart@kvack.org </a>