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Message-ID: <xr93vd478kgx.fsf@ninji.mtv.corp.google.com>
Date: Mon, 08 Nov 2010 15:27:26 -0800
From: Greg Thelen <gthelen@...gle.com>
To: Johannes Weiner <hannes@...xchg.org>
Cc: Minchan Kim <minchan.kim@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Dave Young <hidave.darkstar@...il.com>,
Andrea Righi <arighi@...eler.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
Balbir Singh <balbir@...ux.vnet.ibm.com>,
Wu Fengguang <fengguang.wu@...el.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [patch 4/4] memcg: use native word page statistics counters
Johannes Weiner <hannes@...xchg.org> writes:
> The statistic counters are in units of pages, there is no reason to
> make them 64-bit wide on 32-bit machines.
>
> Make them native words. Since they are signed, this leaves 31 bit on
> 32-bit machines, which can represent roughly 8TB assuming a page size
> of 4k.
>
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> ---
> include/linux/memcontrol.h | 2 +-
> mm/memcontrol.c | 43 +++++++++++++++++++++----------------------
> mm/page-writeback.c | 4 ++--
> 3 files changed, 24 insertions(+), 25 deletions(-)
>
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -110,7 +110,7 @@ enum {
> };
>
> struct mem_cgroup_stat_cpu {
> - s64 count[MEM_CGROUP_STAT_NSTATS];
> + long count[MEM_CGROUP_STAT_NSTATS];
> unsigned long events[MEM_CGROUP_EVENTS_NSTATS];
> };
>
> @@ -583,11 +583,11 @@ mem_cgroup_largest_soft_limit_node(struc
> * common workload, threashold and synchonization as vmstat[] should be
> * implemented.
> */
> -static s64 mem_cgroup_read_stat(struct mem_cgroup *mem,
> - enum mem_cgroup_stat_index idx)
> +static long mem_cgroup_read_stat(struct mem_cgroup *mem,
> + enum mem_cgroup_stat_index idx)
> {
> + long val = 0;
> int cpu;
> - s64 val = 0;
>
> for_each_online_cpu(cpu)
> val += per_cpu(mem->stat->count[idx], cpu);
> @@ -599,9 +599,9 @@ static s64 mem_cgroup_read_stat(struct m
> return val;
> }
>
> -static s64 mem_cgroup_local_usage(struct mem_cgroup *mem)
> +static long mem_cgroup_local_usage(struct mem_cgroup *mem)
> {
> - s64 ret;
> + long ret;
>
> ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_RSS);
> ret += mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_CACHE);
> @@ -1244,7 +1244,7 @@ bool mem_cgroup_dirty_info(unsigned long
> struct vm_dirty_param dirty_param;
> unsigned long available_mem;
> struct mem_cgroup *memcg;
> - s64 value;
> + long value;
>
> if (mem_cgroup_disabled())
> return false;
> @@ -1301,10 +1301,10 @@ static inline bool mem_cgroup_can_swap(s
> (res_counter_read_u64(&memcg->memsw, RES_LIMIT) > 0);
> }
>
> -static s64 mem_cgroup_local_page_stat(struct mem_cgroup *mem,
> - enum mem_cgroup_nr_pages_item item)
> +static long mem_cgroup_local_page_stat(struct mem_cgroup *mem,
> + enum mem_cgroup_nr_pages_item item)
> {
> - s64 ret;
> + long ret;
>
> switch (item) {
> case MEMCG_NR_DIRTYABLE_PAGES:
> @@ -1365,11 +1365,11 @@ memcg_hierarchical_free_pages(struct mem
> * Return the accounted statistic value or negative value if current task is
> * root cgroup.
> */
> -s64 mem_cgroup_page_stat(enum mem_cgroup_nr_pages_item item)
> +long mem_cgroup_page_stat(enum mem_cgroup_nr_pages_item item)
> {
> - struct mem_cgroup *mem;
> struct mem_cgroup *iter;
> - s64 value;
> + struct mem_cgroup *mem;
> + long value;
>
> get_online_cpus();
> rcu_read_lock();
> @@ -2069,7 +2069,7 @@ static void mem_cgroup_drain_pcp_counter
>
> spin_lock(&mem->pcp_counter_lock);
> for (i = 0; i < MEM_CGROUP_STAT_DATA; i++) {
> - s64 x = per_cpu(mem->stat->count[i], cpu);
> + long x = per_cpu(mem->stat->count[i], cpu);
>
> per_cpu(mem->stat->count[i], cpu) = 0;
> mem->nocpu_base.count[i] += x;
> @@ -3660,13 +3660,13 @@ static int mem_cgroup_hierarchy_write(st
> }
>
>
> -static u64 mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
> - enum mem_cgroup_stat_index idx)
> +static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *mem,
> + enum mem_cgroup_stat_index idx)
> {
> struct mem_cgroup *iter;
> - s64 val = 0;
> + long val = 0;
>
> - /* each per cpu's value can be minus.Then, use s64 */
> + /* Per-cpu values can be negative, use a signed accumulator */
> for_each_mem_cgroup_tree(iter, mem)
> val += mem_cgroup_read_stat(iter, idx);
>
> @@ -3686,12 +3686,11 @@ static inline u64 mem_cgroup_usage(struc
> return res_counter_read_u64(&mem->memsw, RES_USAGE);
> }
>
> - val = mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE);
> - val += mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS);
> + val = mem_cgroup_recursive_stat(mem, MEM_CGROUP_STAT_CACHE);
> + val += mem_cgroup_recursive_stat(mem, MEM_CGROUP_STAT_RSS);
>
> if (swap)
> - val += mem_cgroup_get_recursive_idx_stat(mem,
> - MEM_CGROUP_STAT_SWAPOUT);
> + val += mem_cgroup_recursive_stat(mem, MEM_CGROUP_STAT_SWAPOUT);
>
> return val << PAGE_SHIFT;
> }
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -157,7 +157,7 @@ static inline void mem_cgroup_dec_page_s
> bool mem_cgroup_has_dirty_limit(void);
> bool mem_cgroup_dirty_info(unsigned long sys_available_mem,
> struct dirty_info *info);
> -s64 mem_cgroup_page_stat(enum mem_cgroup_nr_pages_item item);
> +long mem_cgroup_page_stat(enum mem_cgroup_nr_pages_item item);
Ooops. I missed something in my review.
mem_cgroup_page_stat() appears twice in memcontrol.h The return value
should match regardless of if CONFIG_CGROUP_MEM_RES_CTLR is set.
I suggest integrating the following into you patch ([patch 4/4] memcg:
use native word page statistics counters):
---
include/linux/memcontrol.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 4e046d6..7a3d915 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -351,7 +351,7 @@ static inline bool mem_cgroup_dirty_info(unsigned long sys_available_mem,
return false;
}
-static inline s64 mem_cgroup_page_stat(enum mem_cgroup_nr_pages_item item)
+static inline long mem_cgroup_page_stat(enum mem_cgroup_nr_pages_item item)
{
return -ENOSYS;
}
> unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
> gfp_t gfp_mask);
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -133,10 +133,10 @@ static struct prop_descriptor vm_dirties
>
> static unsigned long dirty_writeback_pages(void)
> {
> - s64 ret;
> + unsigned long ret;
>
> ret = mem_cgroup_page_stat(MEMCG_NR_DIRTY_WRITEBACK_PAGES);
> - if (ret < 0)
> + if ((long)ret < 0)
> ret = global_page_state(NR_UNSTABLE_NFS) +
> global_page_state(NR_WRITEBACK);
>
--
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