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Message-Id: <20110513185612.84b466ec.kamezawa.hiroyu@jp.fujitsu.com>
Date: Fri, 13 May 2011 18:56:12 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Greg Thelen <gthelen@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
containers@...ts.osdl.org, linux-fsdevel@...r.kernel.org,
Andrea Righi <arighi@...eler.com>,
Balbir Singh <balbir@...ux.vnet.ibm.com>,
Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
Minchan Kim <minchan.kim@...il.com>,
Johannes Weiner <hannes@...xchg.org>,
Ciju Rajan K <ciju@...ux.vnet.ibm.com>,
David Rientjes <rientjes@...gle.com>,
Wu Fengguang <fengguang.wu@...el.com>,
Vivek Goyal <vgoyal@...hat.com>,
Dave Chinner <david@...morbit.com>
Subject: Re: [RFC][PATCH v7 10/14] memcg: dirty page accounting support
routines
On Fri, 13 May 2011 01:47:49 -0700
Greg Thelen <gthelen@...gle.com> wrote:
> Added memcg dirty page accounting support routines. These routines are
> used by later changes to provide memcg aware writeback and dirty page
> limiting. A mem_cgroup_dirty_info() tracepoint is is also included to
> allow for easier understanding of memcg writeback operation.
>
> Signed-off-by: Greg Thelen <gthelen@...gle.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
with small nit..(see below)
> ---
> include/linux/memcontrol.h | 9 +++
> include/trace/events/memcontrol.h | 34 +++++++++
> mm/memcontrol.c | 145 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 188 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index f1261e5..f06c2de 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -36,6 +36,15 @@ enum mem_cgroup_page_stat_item {
> MEMCG_NR_FILE_DIRTY, /* # of dirty pages in page cache */
> MEMCG_NR_FILE_WRITEBACK, /* # of pages under writeback */
> MEMCG_NR_FILE_UNSTABLE_NFS, /* # of NFS unstable pages */
> + MEMCG_NR_DIRTYABLE_PAGES, /* # of pages that could be dirty */
> +};
> +
> +struct dirty_info {
> + unsigned long dirty_thresh;
> + unsigned long background_thresh;
> + unsigned long nr_file_dirty;
> + unsigned long nr_writeback;
> + unsigned long nr_unstable_nfs;
> };
>
> extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
> diff --git a/include/trace/events/memcontrol.h b/include/trace/events/memcontrol.h
> index 781ef9fc..abf1306 100644
> --- a/include/trace/events/memcontrol.h
> +++ b/include/trace/events/memcontrol.h
> @@ -26,6 +26,40 @@ TRACE_EVENT(mem_cgroup_mark_inode_dirty,
> TP_printk("ino=%ld css_id=%d", __entry->ino, __entry->css_id)
> )
>
> +TRACE_EVENT(mem_cgroup_dirty_info,
> + TP_PROTO(unsigned short css_id,
> + struct dirty_info *dirty_info),
> +
> + TP_ARGS(css_id, dirty_info),
> +
> + TP_STRUCT__entry(
> + __field(unsigned short, css_id)
> + __field(unsigned long, dirty_thresh)
> + __field(unsigned long, background_thresh)
> + __field(unsigned long, nr_file_dirty)
> + __field(unsigned long, nr_writeback)
> + __field(unsigned long, nr_unstable_nfs)
> + ),
> +
> + TP_fast_assign(
> + __entry->css_id = css_id;
> + __entry->dirty_thresh = dirty_info->dirty_thresh;
> + __entry->background_thresh = dirty_info->background_thresh;
> + __entry->nr_file_dirty = dirty_info->nr_file_dirty;
> + __entry->nr_writeback = dirty_info->nr_writeback;
> + __entry->nr_unstable_nfs = dirty_info->nr_unstable_nfs;
> + ),
> +
> + TP_printk("css_id=%d thresh=%ld bg_thresh=%ld dirty=%ld wb=%ld "
> + "unstable_nfs=%ld",
> + __entry->css_id,
> + __entry->dirty_thresh,
> + __entry->background_thresh,
> + __entry->nr_file_dirty,
> + __entry->nr_writeback,
> + __entry->nr_unstable_nfs)
> +)
> +
> #endif /* _TRACE_MEMCONTROL_H */
>
> /* This part must be outside protection */
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 248396c..75ef32c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1328,6 +1328,11 @@ static unsigned int get_swappiness(struct mem_cgroup *memcg)
> return memcg->swappiness;
> }
>
> +static unsigned long dirty_info_reclaimable(struct dirty_info *info)
> +{
> + return info->nr_file_dirty + info->nr_unstable_nfs;
> +}
> +
> /*
> * Return true if the current memory cgroup has local dirty memory settings.
> * There is an allowed race between the current task migrating in-to/out-of the
> @@ -1358,6 +1363,146 @@ static void mem_cgroup_dirty_param(struct vm_dirty_param *param,
> }
> }
>
> +static inline bool mem_cgroup_can_swap(struct mem_cgroup *mem)
> +{
> + if (!do_swap_account)
> + return nr_swap_pages > 0;
> + return !mem->memsw_is_minimum &&
> + (res_counter_read_u64(&mem->memsw, RES_LIMIT) > 0);
> +}
> +
> +static s64 mem_cgroup_local_page_stat(struct mem_cgroup *mem,
> + enum mem_cgroup_page_stat_item item)
> +{
> + s64 ret;
> +
> + switch (item) {
> + case MEMCG_NR_FILE_DIRTY:
> + ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_DIRTY);
> + break;
> + case MEMCG_NR_FILE_WRITEBACK:
> + ret = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_WRITEBACK);
> + break;
> + case MEMCG_NR_FILE_UNSTABLE_NFS:
> + ret = mem_cgroup_read_stat(mem,
> + MEM_CGROUP_STAT_FILE_UNSTABLE_NFS);
> + break;
> + case MEMCG_NR_DIRTYABLE_PAGES:
> + ret = mem_cgroup_read_stat(mem, LRU_ACTIVE_FILE) +
> + mem_cgroup_read_stat(mem, LRU_INACTIVE_FILE);
> + if (mem_cgroup_can_swap(mem))
> + ret += mem_cgroup_read_stat(mem, LRU_ACTIVE_ANON) +
> + mem_cgroup_read_stat(mem, LRU_INACTIVE_ANON);
> + break;
> + default:
> + BUG();
> + break;
> + }
> + return ret;
> +}
> +
> +/*
> + * Return the number of additional pages that the @mem cgroup could allocate.
> + * If use_hierarchy is set, then this involves checking parent mem cgroups to
> + * find the cgroup with the smallest free space.
> + */
> +static unsigned long
> +mem_cgroup_hierarchical_free_pages(struct mem_cgroup *mem)
> +{
> + u64 free;
> + unsigned long min_free;
> +
> + min_free = global_page_state(NR_FREE_PAGES);
> +
> + while (mem) {
> + free = (res_counter_read_u64(&mem->res, RES_LIMIT) -
> + res_counter_read_u64(&mem->res, RES_USAGE)) >>
> + PAGE_SHIFT;
> + min_free = min((u64)min_free, free);
> + mem = parent_mem_cgroup(mem);
> + }
> +
> + return min_free;
> +}
> +
> +/*
> + * mem_cgroup_page_stat() - get memory cgroup file cache statistics
> + * @mem: memory cgroup to query
> + * @item: memory statistic item exported to the kernel
> + *
> + * Return the accounted statistic value.
> + */
> +static unsigned long mem_cgroup_page_stat(struct mem_cgroup *mem,
> + enum mem_cgroup_page_stat_item item)
How about mem_cgroup_file_cache_stat() ?
> +{
> + struct mem_cgroup *iter;
> + s64 value;
> +
> + /*
> + * If we're looking for dirtyable pages we need to evaluate free pages
> + * depending on the limit and usage of the parents first of all.
> + */
> + if (item == MEMCG_NR_DIRTYABLE_PAGES)
> + value = mem_cgroup_hierarchical_free_pages(mem);
> + else
> + value = 0;
> +
> + /*
> + * Recursively evaluate page statistics against all cgroup under
> + * hierarchy tree
> + */
> + for_each_mem_cgroup_tree(iter, mem)
> + value += mem_cgroup_local_page_stat(iter, item);
> +
> + /*
> + * Summing of unlocked per-cpu counters is racy and may yield a slightly
> + * negative value. Zero is the only sensible value in such cases.
> + */
> + if (unlikely(value < 0))
> + value = 0;
> +
> + return value;
> +}
seems very nice handling of hierarchy :)
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