As per an earlier discussion on the lkml, the existing prefetch in
free_one_pgd() is somewhat broken in that it prefetches further than
PREFETCH_STRIDE bytes. The patch below fixes that. I'm told that
this also performs better on x86 (it makes little difference on ia64,
but it is also marginally better).
--david
diff -Nru a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c Thu Aug 1 17:02:14 2002
+++ b/mm/memory.c Thu Aug 1 17:02:14 2002
@@ -110,7 +110,7 @@
pmd = pmd_offset(dir, 0);
pgd_clear(dir);
for (j = 0; j < PTRS_PER_PMD ; j++) {
- prefetchw(pmd+j+(PREFETCH_STRIDE/16));
+ prefetchw(pmd + j + PREFETCH_STRIDE/sizeof(*pmd));
free_one_pmd(tlb, pmd+j);
}
pmd_free_tlb(tlb, pmd);
-
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