On Tue, Mar 09, 2010 at 10:29:28AM +0900, Daisuke Nishimura wrote: > On Tue, 9 Mar 2010 09:19:14 +0900, KAMEZAWA Hiroyuki > <[email protected]> wrote: > > On Tue, 9 Mar 2010 01:12:52 +0100 > > Andrea Righi <[email protected]> wrote: > > > > > On Mon, Mar 08, 2010 at 05:31:00PM +0900, KAMEZAWA Hiroyuki wrote: > > > > On Mon, 8 Mar 2010 17:07:11 +0900 > > > > Daisuke Nishimura <[email protected]> wrote: > > > > > > > > > On Mon, 8 Mar 2010 11:37:11 +0900, KAMEZAWA Hiroyuki > > > > > <[email protected]> wrote: > > > > > > On Mon, 8 Mar 2010 11:17:24 +0900 > > > > > > Daisuke Nishimura <[email protected]> wrote: > > > > > > > > > > > > > > But IIRC, clear_writeback is done under treelock.... No ? > > > > > > > > > > > > > > > The place where NR_WRITEBACK is updated is out of tree_lock. > > > > > > > > > > > > > > 1311 int test_clear_page_writeback(struct page *page) > > > > > > > 1312 { > > > > > > > 1313 struct address_space *mapping = > > > > > > > page_mapping(page); > > > > > > > 1314 int ret; > > > > > > > 1315 > > > > > > > 1316 if (mapping) { > > > > > > > 1317 struct backing_dev_info *bdi = > > > > > > > mapping->backing_dev_info; > > > > > > > 1318 unsigned long flags; > > > > > > > 1319 > > > > > > > 1320 spin_lock_irqsave(&mapping->tree_lock, > > > > > > > flags); > > > > > > > 1321 ret = TestClearPageWriteback(page); > > > > > > > 1322 if (ret) { > > > > > > > 1323 > > > > > > > radix_tree_tag_clear(&mapping->page_tree, > > > > > > > 1324 > > > > > > > page_index(page), > > > > > > > 1325 > > > > > > > PAGECACHE_TAG_WRITEBACK); > > > > > > > 1326 if > > > > > > > (bdi_cap_account_writeback(bdi)) { > > > > > > > 1327 __dec_bdi_stat(bdi, > > > > > > > BDI_WRITEBACK); > > > > > > > 1328 __bdi_writeout_inc(bdi); > > > > > > > 1329 } > > > > > > > 1330 } > > > > > > > 1331 > > > > > > > spin_unlock_irqrestore(&mapping->tree_lock, flags); > > > > > > > 1332 } else { > > > > > > > 1333 ret = TestClearPageWriteback(page); > > > > > > > 1334 } > > > > > > > 1335 if (ret) > > > > > > > 1336 dec_zone_page_state(page, NR_WRITEBACK); > > > > > > > 1337 return ret; > > > > > > > 1338 } > > > > > > > > > > > > We can move this up to under tree_lock. Considering memcg, all our > > > > > > target has "mapping". > > > > > > > > > > > > If we newly account bounce-buffers (for NILFS, FUSE, etc..), which > > > > > > has no ->mapping, > > > > > > we need much more complex new charge/uncharge theory. > > > > > > > > > > > > But yes, adding new lock scheme seems complicated. (Sorry Andrea.) > > > > > > My concerns is performance. We may need somehing new > > > > > > re-implementation of > > > > > > locks/migrate/charge/uncharge. > > > > > > > > > > > I agree. Performance is my concern too. > > > > > > > > > > I made a patch below and measured the time(average of 10 times) of > > > > > kernel build > > > > > on tmpfs(make -j8 on 8 CPU machine with 2.6.33 defconfig). > > > > > > > > > > <before> > > > > > - root cgroup: 190.47 sec > > > > > - child cgroup: 192.81 sec > > > > > > > > > > <after> > > > > > - root cgroup: 191.06 sec > > > > > - child cgroup: 193.06 sec > > > > > > > > > > Hmm... about 0.3% slower for root, 0.1% slower for child. > > > > > > > > > > > > > Hmm...accepatable ? (sounds it's in error-range) > > > > > > > > BTW, why local_irq_disable() ? > > > > local_irq_save()/restore() isn't better ? > > > > > > Probably there's not the overhead of saving flags? > > maybe. > > > > > Anyway, it would make the code much more readable... > > > > > ok. > > > > please go ahead in this direction. Nishimura-san, would you post an > > independent patch ? If no, Andrea-san, please. > > > This is the updated version. > > Andrea-san, can you merge this into your patch set ?
OK, I'll merge, do some tests and post a new version. Thanks! -Andrea > > === > From: Daisuke Nishimura <[email protected]> > > In current implementation, we don't have to disable irq at lock_page_cgroup() > because the lock is never acquired in interrupt context. > But we are going to call it in later patch in an interrupt context or with > irq disabled, so this patch disables irq at lock_page_cgroup() and enables it > at unlock_page_cgroup(). > > Signed-off-by: Daisuke Nishimura <[email protected]> > --- > include/linux/page_cgroup.h | 16 ++++++++++++++-- > mm/memcontrol.c | 43 > +++++++++++++++++++++++++------------------ > 2 files changed, 39 insertions(+), 20 deletions(-) > > diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h > index 30b0813..0d2f92c 100644 > --- a/include/linux/page_cgroup.h > +++ b/include/linux/page_cgroup.h > @@ -83,16 +83,28 @@ static inline enum zone_type page_cgroup_zid(struct > page_cgroup *pc) > return page_zonenum(pc->page); > } > > -static inline void lock_page_cgroup(struct page_cgroup *pc) > +static inline void __lock_page_cgroup(struct page_cgroup *pc) > { > bit_spin_lock(PCG_LOCK, &pc->flags); > } > > -static inline void unlock_page_cgroup(struct page_cgroup *pc) > +static inline void __unlock_page_cgroup(struct page_cgroup *pc) > { > bit_spin_unlock(PCG_LOCK, &pc->flags); > } > > +#define lock_page_cgroup(pc, flags) \ > + do { \ > + local_irq_save(flags); \ > + __lock_page_cgroup(pc); \ > + } while (0) > + > +#define unlock_page_cgroup(pc, flags) \ > + do { \ > + __unlock_page_cgroup(pc); \ > + local_irq_restore(flags); \ > + } while (0) > + > #else /* CONFIG_CGROUP_MEM_RES_CTLR */ > struct page_cgroup; > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 7fab84e..a9fd736 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1352,12 +1352,13 @@ void mem_cgroup_update_file_mapped(struct page *page, > int val) > { > struct mem_cgroup *mem; > struct page_cgroup *pc; > + unsigned long flags; > > pc = lookup_page_cgroup(page); > if (unlikely(!pc)) > return; > > - lock_page_cgroup(pc); > + lock_page_cgroup(pc, flags); > mem = pc->mem_cgroup; > if (!mem) > goto done; > @@ -1371,7 +1372,7 @@ void mem_cgroup_update_file_mapped(struct page *page, > int val) > __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED], val); > > done: > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > } > > /* > @@ -1705,11 +1706,12 @@ struct mem_cgroup > *try_get_mem_cgroup_from_page(struct page *page) > struct page_cgroup *pc; > unsigned short id; > swp_entry_t ent; > + unsigned long flags; > > VM_BUG_ON(!PageLocked(page)); > > pc = lookup_page_cgroup(page); > - lock_page_cgroup(pc); > + lock_page_cgroup(pc, flags); > if (PageCgroupUsed(pc)) { > mem = pc->mem_cgroup; > if (mem && !css_tryget(&mem->css)) > @@ -1723,7 +1725,7 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct > page *page) > mem = NULL; > rcu_read_unlock(); > } > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > return mem; > } > > @@ -1736,13 +1738,15 @@ static void __mem_cgroup_commit_charge(struct > mem_cgroup *mem, > struct page_cgroup *pc, > enum charge_type ctype) > { > + unsigned long flags; > + > /* try_charge() can return NULL to *memcg, taking care of it. */ > if (!mem) > return; > > - lock_page_cgroup(pc); > + lock_page_cgroup(pc, flags); > if (unlikely(PageCgroupUsed(pc))) { > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > mem_cgroup_cancel_charge(mem); > return; > } > @@ -1772,7 +1776,7 @@ static void __mem_cgroup_commit_charge(struct > mem_cgroup *mem, > > mem_cgroup_charge_statistics(mem, pc, true); > > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > /* > * "charge_statistics" updated event counter. Then, check it. > * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree. > @@ -1842,12 +1846,13 @@ static int mem_cgroup_move_account(struct page_cgroup > *pc, > struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge) > { > int ret = -EINVAL; > - lock_page_cgroup(pc); > + unsigned long flags; > + lock_page_cgroup(pc, flags); > if (PageCgroupUsed(pc) && pc->mem_cgroup == from) { > __mem_cgroup_move_account(pc, from, to, uncharge); > ret = 0; > } > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > /* > * check events > */ > @@ -1974,17 +1979,17 @@ int mem_cgroup_cache_charge(struct page *page, struct > mm_struct *mm, > */ > if (!(gfp_mask & __GFP_WAIT)) { > struct page_cgroup *pc; > - > + unsigned long flags; > > pc = lookup_page_cgroup(page); > if (!pc) > return 0; > - lock_page_cgroup(pc); > + lock_page_cgroup(pc, flags); > if (PageCgroupUsed(pc)) { > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > return 0; > } > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > } > > if (unlikely(!mm && !mem)) > @@ -2166,6 +2171,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum > charge_type ctype) > struct page_cgroup *pc; > struct mem_cgroup *mem = NULL; > struct mem_cgroup_per_zone *mz; > + unsigned long flags; > > if (mem_cgroup_disabled()) > return NULL; > @@ -2180,7 +2186,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum > charge_type ctype) > if (unlikely(!pc || !PageCgroupUsed(pc))) > return NULL; > > - lock_page_cgroup(pc); > + lock_page_cgroup(pc, flags); > > mem = pc->mem_cgroup; > > @@ -2219,7 +2225,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum > charge_type ctype) > */ > > mz = page_cgroup_zoneinfo(pc); > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > > memcg_check_events(mem, page); > /* at swapout, this memcg will be accessed to record to swap */ > @@ -2229,7 +2235,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum > charge_type ctype) > return mem; > > unlock_out: > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > return NULL; > } > > @@ -2417,17 +2423,18 @@ int mem_cgroup_prepare_migration(struct page *page, > struct mem_cgroup **ptr) > struct page_cgroup *pc; > struct mem_cgroup *mem = NULL; > int ret = 0; > + unsigned long flags; > > if (mem_cgroup_disabled()) > return 0; > > pc = lookup_page_cgroup(page); > - lock_page_cgroup(pc); > + lock_page_cgroup(pc, flags); > if (PageCgroupUsed(pc)) { > mem = pc->mem_cgroup; > css_get(&mem->css); > } > - unlock_page_cgroup(pc); > + unlock_page_cgroup(pc, flags); > > if (mem) { > ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false); > -- > 1.6.4 > _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
