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Date: Thu, 10 Feb 2011 08:54:57 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Johannes Weiner <hannes@...xchg.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
Balbir Singh <balbir@...ux.vnet.ibm.com>, <linux-mm@...ck.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [patch 4/4] memcg: unify charge/uncharge quantities to units of
pages
On Wed, 9 Feb 2011 12:01:53 +0100
Johannes Weiner <hannes@...xchg.org> wrote:
> There is no clear pattern when we pass a page count and when we pass a
> byte count that is a multiple of PAGE_SIZE.
>
> We never charge or uncharge subpage quantities, so convert it all to
> page counts.
>
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> ---
> mm/memcontrol.c | 117 +++++++++++++++++++++++++-----------------------------
> 1 files changed, 54 insertions(+), 63 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index ab5cd3b..bc03f56 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1083,16 +1083,16 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
> * @mem: the memory cgroup
> *
> * Returns the maximum amount of memory @mem can be charged with, in
> - * bytes.
> + * pages.
> */
> -static unsigned long long mem_cgroup_margin(struct mem_cgroup *mem)
> +static unsigned long mem_cgroup_margin(struct mem_cgroup *mem)
> {
> unsigned long long margin;
>
> margin = res_counter_margin(&mem->res);
> if (do_swap_account)
> margin = min(margin, res_counter_margin(&mem->memsw));
> - return margin;
> + return margin >> PAGE_SHIFT;
> }
>
> static unsigned int get_swappiness(struct mem_cgroup *memcg)
> @@ -1621,7 +1621,7 @@ EXPORT_SYMBOL(mem_cgroup_update_page_stat);
> * size of first charge trial. "32" comes from vmscan.c's magic value.
> * TODO: maybe necessary to use big numbers in big irons.
> */
> -#define CHARGE_SIZE (32 * PAGE_SIZE)
> +#define CHARGE_BATCH 32U
> struct memcg_stock_pcp {
> struct mem_cgroup *cached; /* this never be root cgroup */
> unsigned int nr_pages;
> @@ -1797,8 +1797,9 @@ enum {
> };
>
> static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
> - int csize, bool oom_check)
> + unsigned int nr_pages, bool oom_check)
> {
> + unsigned long csize = nr_pages * PAGE_SIZE;
> struct mem_cgroup *mem_over_limit;
> struct res_counter *fail_res;
> unsigned long flags = 0;
> @@ -1819,14 +1820,13 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
> } else
> mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
> /*
> - * csize can be either a huge page (HPAGE_SIZE), a batch of
> - * regular pages (CHARGE_SIZE), or a single regular page
> - * (PAGE_SIZE).
> + * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch
> + * of regular pages (CHARGE_BATCH), or a single regular page (1).
> *
> * Never reclaim on behalf of optional batching, retry with a
> * single page instead.
> */
> - if (csize == CHARGE_SIZE)
> + if (nr_pages == CHARGE_BATCH)
> return CHARGE_RETRY;
>
> if (!(gfp_mask & __GFP_WAIT))
> @@ -1834,7 +1834,7 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
>
> ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
> gfp_mask, flags);
> - if (mem_cgroup_margin(mem_over_limit) >= csize)
> + if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
> return CHARGE_RETRY;
> /*
> * Even though the limit is exceeded at this point, reclaim
> @@ -1845,7 +1845,7 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
> * unlikely to succeed so close to the limit, and we fall back
> * to regular pages anyway in case of failure.
> */
> - if (csize == PAGE_SIZE && ret)
> + if (nr_pages == 1 && ret)
> return CHARGE_RETRY;
>
> /*
> @@ -1872,12 +1872,12 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
> static int __mem_cgroup_try_charge(struct mm_struct *mm,
> gfp_t gfp_mask,
> struct mem_cgroup **memcg, bool oom,
> - int page_size)
> + unsigned int nr_pages)
> {
> + unsigned int batch = max(CHARGE_BATCH, nr_pages);
> int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
> struct mem_cgroup *mem = NULL;
> int ret;
> - int csize = max(CHARGE_SIZE, (unsigned long) page_size);
>
> /*
> * Unlike gloval-vm's OOM-kill, we're not in memory shortage
> @@ -1902,7 +1902,7 @@ again:
> VM_BUG_ON(css_is_removed(&mem->css));
> if (mem_cgroup_is_root(mem))
> goto done;
> - if (page_size == PAGE_SIZE && consume_stock(mem))
> + if (nr_pages == 1 && consume_stock(mem))
> goto done;
> css_get(&mem->css);
> } else {
> @@ -1925,7 +1925,7 @@ again:
> rcu_read_unlock();
> goto done;
> }
> - if (page_size == PAGE_SIZE && consume_stock(mem)) {
> + if (nr_pages == 1 && consume_stock(mem)) {
> /*
> * It seems dagerous to access memcg without css_get().
> * But considering how consume_stok works, it's not
> @@ -1960,13 +1960,12 @@ again:
> nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
> }
>
> - ret = __mem_cgroup_do_charge(mem, gfp_mask, csize, oom_check);
> -
> + ret = __mem_cgroup_do_charge(mem, gfp_mask, batch, oom_check);
> switch (ret) {
> case CHARGE_OK:
> break;
> case CHARGE_RETRY: /* not in OOM situation but retry */
> - csize = page_size;
> + batch = nr_pages;
> css_put(&mem->css);
> mem = NULL;
> goto again;
> @@ -1987,8 +1986,8 @@ again:
> }
> } while (ret != CHARGE_OK);
>
> - if (csize > page_size)
> - refill_stock(mem, (csize - page_size) >> PAGE_SHIFT);
> + if (batch > nr_pages)
> + refill_stock(mem, batch - nr_pages);
> css_put(&mem->css);
> done:
> *memcg = mem;
> @@ -2069,10 +2068,8 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
> struct page *page,
> struct page_cgroup *pc,
> enum charge_type ctype,
> - int page_size)
> + unsigned int nr_pages)
> {
> - int nr_pages = page_size >> PAGE_SHIFT;
> -
> lock_page_cgroup(pc);
> if (unlikely(PageCgroupUsed(pc))) {
> unlock_page_cgroup(pc);
> @@ -2165,11 +2162,11 @@ void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail)
> * @from: mem_cgroup which the page is moved from.
> * @to: mem_cgroup which the page is moved to. @from != @to.
> * @uncharge: whether we should call uncharge and css_put against @from.
> - * @charge_size: number of bytes to charge (regular or huge page)
> + * @nr_pages: number of regular pages (>1 for huge pages)
> *
> * The caller must confirm following.
> * - page is not on LRU (isolate_page() is useful.)
> - * - compound_lock is held when charge_size > PAGE_SIZE
> + * - compound_lock is held when nr_pages > 1
> *
> * This function doesn't do "charge" nor css_get to new cgroup. It should be
> * done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is
> @@ -2178,9 +2175,8 @@ void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail)
> */
> static int mem_cgroup_move_account(struct page *page, struct page_cgroup *pc,
> struct mem_cgroup *from, struct mem_cgroup *to,
> - bool uncharge, int charge_size)
> + bool uncharge, unsigned int nr_pages)
> {
> - int nr_pages = charge_size >> PAGE_SHIFT;
> unsigned long flags;
> int ret;
>
> @@ -2193,7 +2189,7 @@ static int mem_cgroup_move_account(struct page *page, struct page_cgroup *pc,
> * hold it.
> */
> ret = -EBUSY;
> - if (charge_size > PAGE_SIZE && !PageTransHuge(page))
> + if (nr_pages > 1 && !PageTransHuge(page))
> goto out;
>
> lock_page_cgroup(pc);
> @@ -2251,7 +2247,7 @@ static int mem_cgroup_move_parent(struct page *page,
> struct cgroup *cg = child->css.cgroup;
> struct cgroup *pcg = cg->parent;
> struct mem_cgroup *parent;
> - int page_size = PAGE_SIZE;
> + unsigned int nr_pages;
> unsigned long flags;
> int ret;
>
> @@ -2265,23 +2261,21 @@ static int mem_cgroup_move_parent(struct page *page,
> if (isolate_lru_page(page))
> goto put;
>
> - if (PageTransHuge(page))
> - page_size = HPAGE_SIZE;
> + nr_pages = hpage_nr_pages(page);
>
> parent = mem_cgroup_from_cont(pcg);
> - ret = __mem_cgroup_try_charge(NULL, gfp_mask,
> - &parent, false, page_size);
> + ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false, nr_pages);
> if (ret || !parent)
> goto put_back;
>
> - if (page_size > PAGE_SIZE)
> + if (nr_pages > 1)
> flags = compound_lock_irqsave(page);
>
> - ret = mem_cgroup_move_account(page, pc, child, parent, true, page_size);
> + ret = mem_cgroup_move_account(page, pc, child, parent, true, nr_pages);
> if (ret)
> - mem_cgroup_cancel_charge(parent, page_size >> PAGE_SHIFT);
> + mem_cgroup_cancel_charge(parent, nr_pages);
>
> - if (page_size > PAGE_SIZE)
> + if (nr_pages > 1)
> compound_unlock_irqrestore(page, flags);
> put_back:
> putback_lru_page(page);
> @@ -2301,13 +2295,13 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
> gfp_t gfp_mask, enum charge_type ctype)
> {
> struct mem_cgroup *mem = NULL;
> - int page_size = PAGE_SIZE;
> + unsigned int nr_pages = 1;
> struct page_cgroup *pc;
> bool oom = true;
> int ret;
>
> if (PageTransHuge(page)) {
> - page_size <<= compound_order(page);
> + nr_pages <<= compound_order(page);
> VM_BUG_ON(!PageTransHuge(page));
> /*
> * Never OOM-kill a process for a huge page. The
> @@ -2319,11 +2313,11 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
> pc = lookup_page_cgroup(page);
> BUG_ON(!pc); /* XXX: remove this and move pc lookup into commit */
>
> - ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, oom, page_size);
> + ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, oom, nr_pages);
> if (ret || !mem)
> return ret;
>
> - __mem_cgroup_commit_charge(mem, page, pc, ctype, page_size);
> + __mem_cgroup_commit_charge(mem, page, pc, ctype, nr_pages);
> return 0;
> }
>
> @@ -2439,13 +2433,13 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
> if (!mem)
> goto charge_cur_mm;
> *ptr = mem;
> - ret = __mem_cgroup_try_charge(NULL, mask, ptr, true, PAGE_SIZE);
> + ret = __mem_cgroup_try_charge(NULL, mask, ptr, true, 1);
> css_put(&mem->css);
> return ret;
> charge_cur_mm:
> if (unlikely(!mm))
> mm = &init_mm;
> - return __mem_cgroup_try_charge(mm, mask, ptr, true, PAGE_SIZE);
> + return __mem_cgroup_try_charge(mm, mask, ptr, true, 1);
> }
>
> static void
> @@ -2461,7 +2455,7 @@ __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
> cgroup_exclude_rmdir(&ptr->css);
> pc = lookup_page_cgroup(page);
> mem_cgroup_lru_del_before_commit_swapcache(page);
> - __mem_cgroup_commit_charge(ptr, page, pc, ctype, PAGE_SIZE);
> + __mem_cgroup_commit_charge(ptr, page, pc, ctype, 1);
> mem_cgroup_lru_add_after_commit_swapcache(page);
> /*
> * Now swap is on-memory. This means this page may be
> @@ -2515,10 +2509,11 @@ void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
>
> static void
> __do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype,
> - int page_size)
> + unsigned int nr_pages)
> {
> struct memcg_batch_info *batch = NULL;
> bool uncharge_memsw = true;
> +
> /* If swapout, usage of swap doesn't decrease */
> if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
> uncharge_memsw = false;
> @@ -2542,7 +2537,7 @@ __do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype,
> if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
> goto direct_uncharge;
>
> - if (page_size != PAGE_SIZE)
> + if (nr_pages > 1)
> goto direct_uncharge;
>
> /*
> @@ -2558,9 +2553,9 @@ __do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype,
> batch->memsw_nr_pages++;
> return;
> direct_uncharge:
> - res_counter_uncharge(&mem->res, page_size);
> + res_counter_uncharge(&mem->res, nr_pages * PAGE_SIZE);
> if (uncharge_memsw)
> - res_counter_uncharge(&mem->memsw, page_size);
> + res_counter_uncharge(&mem->memsw, nr_pages * PAGE_SIZE);
> if (unlikely(batch->memcg != mem))
> memcg_oom_recover(mem);
> return;
> @@ -2572,10 +2567,9 @@ direct_uncharge:
> static struct mem_cgroup *
> __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
> {
> - int count;
> - struct page_cgroup *pc;
> struct mem_cgroup *mem = NULL;
> - int page_size = PAGE_SIZE;
> + unsigned int nr_pages = 1;
> + struct page_cgroup *pc;
>
> if (mem_cgroup_disabled())
> return NULL;
> @@ -2584,11 +2578,9 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
> return NULL;
>
> if (PageTransHuge(page)) {
> - page_size <<= compound_order(page);
> + nr_pages <<= compound_order(page);
> VM_BUG_ON(!PageTransHuge(page));
> }
> -
> - count = page_size >> PAGE_SHIFT;
> /*
> * Check if our page_cgroup is valid
> */
> @@ -2621,7 +2613,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
> break;
> }
>
> - mem_cgroup_charge_statistics(mem, PageCgroupCache(pc), -count);
> + mem_cgroup_charge_statistics(mem, PageCgroupCache(pc), -nr_pages);
>
> ClearPageCgroupUsed(pc);
> /*
> @@ -2642,7 +2634,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
> mem_cgroup_get(mem);
> }
> if (!mem_cgroup_is_root(mem))
> - __do_uncharge(mem, ctype, page_size);
> + __do_uncharge(mem, ctype, nr_pages);
>
> return mem;
>
> @@ -2834,8 +2826,8 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
> int mem_cgroup_prepare_migration(struct page *page,
> struct page *newpage, struct mem_cgroup **ptr, gfp_t gfp_mask)
> {
> - struct page_cgroup *pc;
> struct mem_cgroup *mem = NULL;
> + struct page_cgroup *pc;
> enum charge_type ctype;
> int ret = 0;
>
> @@ -2891,7 +2883,7 @@ int mem_cgroup_prepare_migration(struct page *page,
> return 0;
>
> *ptr = mem;
> - ret = __mem_cgroup_try_charge(NULL, gfp_mask, ptr, false, PAGE_SIZE);
> + ret = __mem_cgroup_try_charge(NULL, gfp_mask, ptr, false, 1);
> css_put(&mem->css);/* drop extra refcnt */
> if (ret || *ptr == NULL) {
> if (PageAnon(page)) {
> @@ -2918,7 +2910,7 @@ int mem_cgroup_prepare_migration(struct page *page,
> ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
> else
> ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
> - __mem_cgroup_commit_charge(mem, page, pc, ctype, PAGE_SIZE);
> + __mem_cgroup_commit_charge(mem, page, pc, ctype, 1);
> return ret;
> }
>
> @@ -4572,8 +4564,7 @@ one_by_one:
> batch_count = PRECHARGE_COUNT_AT_ONCE;
> cond_resched();
> }
> - ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false,
> - PAGE_SIZE);
> + ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false, 1);
> if (ret || !mem)
> /* mem_cgroup_clear_mc() will do uncharge later */
> return -ENOMEM;
> @@ -4918,8 +4909,8 @@ retry:
> if (isolate_lru_page(page))
> goto put;
> pc = lookup_page_cgroup(page);
> - if (!mem_cgroup_move_account(page, pc,
> - mc.from, mc.to, false, PAGE_SIZE)) {
> + if (!mem_cgroup_move_account(page, pc, mc.from,
> + mc.to, false, 1)) {
> mc.precharge--;
> /* we uncharge from mc.from later. */
> mc.moved_charge++;
> --
> 1.7.4
>
>
--
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