[PATCH] less tlb flush in unmap_vmas

Shaohua Li
2006-03-22T02:39:25Z

In unmaping region, if current task doesn't need reschedule, don't do a
tlb_finish_mmu. This can reduce some tlb flushes.

In the lmbench tests, this patch gives 2.1% improvement on exec proc
item and 4.2% on sh proc item.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
---

linux-2.6.16-rc5-root/mm/memory.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)

diff -puN mm/memory.c~less_flush mm/memory.c
--- linux-2.6.16-rc5/mm/memory.c~less_flush 2006-03-21 07:22:47.000000000 +0800
+++ linux-2.6.16-rc5-root/mm/memory.c 2006-03-21 07:26:51.000000000 +0800
@@ -837,19 +837,18 @@ unsigned long unmap_vmas(struct mmu_gath
break;
}

- tlb_finish_mmu(*tlbp, tlb_start, start);
-
if (need_resched() ||
(i_mmap_lock && need_lockbreak(i_mmap_lock))) {
+ tlb_finish_mmu(*tlbp, tlb_start, start);
if (i_mmap_lock) {
*tlbp = NULL;
goto out;
}
cond_resched();
+ tlb_start_valid = 0;
+ *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
}

- *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
- tlb_start_valid = 0;
zap_work = ZAP_BLOCK_SIZE;
}
}
_