Messages in this thread | | | Date | Wed, 27 May 2009 15:30:24 +0900 | From | Daisuke Nishimura <> | Subject | Re: [RFC][PATCH 5/5] (experimental) chase and free cache only swap |
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On Wed, 27 May 2009 14:14:42 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > 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 ? I think so too, except some trivial build errors ;)
I'll test it, but it will take a long time to see the effect of this patch even if setting the swap space to reasonable size.
Thanks, Daisuke Nishimura.
> 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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