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Message-ID: <BANLkTin6_CiP-Q8MyN=PKhpUhGhdmUQyEA@mail.gmail.com>
Date: Sun, 15 May 2011 12:56:00 -0700
From: Greg Thelen <gthelen@...gle.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.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, May 13, 2011 at 2:56 AM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@...fujitsu.com> wrote:
> 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() ?
The suggested rename is possible. But for consistency I assume we
would also want to rename:
* mem_cgroup_local_page_stat()
* enum mem_cgroup_page_stat_item
* mem_cgroup_update_page_stat()
* mem_cgroup_move_account_page_stat()
I have a slight preference for leaving it as is,
mem_cgroup_page_stat(), to allow for future coverage of pages other
that just file cache pages. But I do not feel very strongly.
>> +{
>> + 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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