Messages in this thread Patch in this message |  | | | Date | Wed, 27 May 2009 14:14:42 +0900 | | From | KAMEZAWA Hiroyuki <> | | Subject | Re: [RFC][PATCH 5/5] (experimental) chase and free cache only swap |
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On Tue, 26 May 2009 12:18:34 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > This is a replacement for this. (just an idea, not testd.)
I think this works well. Does anyone has concerns ? Do I have to modify swap-cluster code to do this in sane way ?
--- mm/swapfile.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) Index: new-trial-swapcount/mm/swapfile.c =================================================================== --- new-trial-swapcount.orig/mm/swapfile.c +++ new-trial-swapcount/mm/swapfile.c @@ -74,6 +74,26 @@ static inline unsigned short make_swap_c return ret; } +static int try_to_reuse_swap(struct swap_info_struct *si, unsigned long offset) +{ + int type = si - swap_info; + swp_entry_t entry = swp_entry(type, offset); + struct page *page; + + page = find_get_page(page); + if (!page) + return 0; + if (!trylock_page(page)) { + page_cache_release(page); + return 0; + } + try_to_free_swap(page); + unlock_page(page); + page_cache_release(page); + return 1; +} + + /* * We need this because the bdev->unplug_fn can sleep and we cannot * hold swap_lock while calling the unplug_fn. And swap_lock @@ -295,6 +315,18 @@ checks: goto no_page; if (offset > si->highest_bit) scan_base = offset = si->lowest_bit; + + /* reuse swap entry of cache-only swap if not busy. */ + if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { + int ret; + spin_unlock(&swap_lock); + ret = try_to_reuse_swap(si, offset)); + spin_lock(&swap_lock); + if (ret) + goto checks; /* we released swap_lock */ + goto scan; + } + if (si->swap_map[offset]) goto scan; @@ -378,6 +410,10 @@ scan: spin_lock(&swap_lock); goto checks; } + if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { + spin_lock(&swap_lock); + goto checks; + } if (unlikely(--latency_ration < 0)) { cond_resched(); latency_ration = LATENCY_LIMIT; @@ -389,6 +425,10 @@ scan: spin_lock(&swap_lock); goto checks; } + if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { + spin_lock(&swap_lock); + goto checks; + } if (unlikely(--latency_ration < 0)) { cond_resched(); latency_ration = LATENCY_LIMIT;
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