diff options
| author | Hugh Dickins <hugh@veritas.com> | 2006-03-16 23:04:09 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-17 07:51:26 -0800 |
| commit | 6f5e6b9e69bf043074a0edabe3d271899c34eb79 (patch) | |
| tree | 8833d7267d6653a2bf786b055f05640c9a64dc4d | |
| parent | 7670f023aabd976c25862e4c6fb9f6d9d2758153 (diff) | |
[PATCH] fix free swap cache latency
Lee Revell reported 28ms latency when process with lots of swapped memory
exits.
2.6.15 introduced a latency regression when unmapping: in accounting the
zap_work latency breaker, pte_none counted 1, pte_present PAGE_SIZE, but a
swap entry counted nothing at all. We think of pages present as the slow
case, but Lee's trace shows that free_swap_and_cache's radix tree lookup
can make a lot of work - and we could have been doing it many thousands of
times without a latency break.
Move the zap_work update up to account swap entries like pages present.
This does account non-linear pte_file entries, and unmap_mapping_range
skipping over swap entries, by the same amount even though they're quick:
but neither of those cases deserves complicating the code (and they're
treated no worse than they were in 2.6.14).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | mm/memory.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c index 9abc6008544..85e80a57db2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -623,11 +623,12 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, (*zap_work)--; continue; } + + (*zap_work) -= PAGE_SIZE; + if (pte_present(ptent)) { struct page *page; - (*zap_work) -= PAGE_SIZE; - page = vm_normal_page(vma, addr, ptent); if (unlikely(details) && page) { /* |