Messages in this thread | | | Date | Wed, 27 May 2009 15:50:55 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [RFC][PATCH 5/5] (experimental) chase and free cache only swap |
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On Wed, 27 May 2009 15:30:24 +0900 Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> 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 ;) > Oh, will be fixed in the next post :(
> 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. > Yes, Hot-to-test is my concern, too..
Thanks, -Kame
> > 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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