Re: [PATCH v8 03/12] memcg: add mem_cgroup_mark_inode_dirty()

[Greg Thelen <gthelen@google.com>]

On Fri, Jun 3, 2011 at 4:09 PM, Andrea Righi <arighi@develer.com> wrote:
> On Fri, Jun 03, 2011 at 09:12:09AM -0700, Greg Thelen wrote:
> ...
>> diff --git a/fs/inode.c b/fs/inode.c
>> index ce61a1b..9ecb0bb 100644
>> --- a/fs/inode.c
>> +++ b/fs/inode.c
>> @@ -228,6 +228,9 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
>>       mapping->assoc_mapping = NULL;
>>       mapping->backing_dev_info = &default_backing_dev_info;
>>       mapping->writeback_index = 0;
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
>> +     mapping->i_memcg = 0;
>> +#endif
>
> It won't change too much, since it's always 0, but shouldn't we use
> I_MEMCG_SHARED by default?

I agree, I_MEMCG_SHARED should be used instead of 0.  Will include in
-v9, if there is a need for -v9.

>>       /*
>>        * If the block_device provides a backing_dev_info for client
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 29c02f6..deabca3 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -645,6 +645,9 @@ struct address_space {
>>       spinlock_t              private_lock;   /* for use by the address_space */
>>       struct list_head        private_list;   /* ditto */
>>       struct address_space    *assoc_mapping; /* ditto */
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
>> +     unsigned short          i_memcg;        /* css_id of memcg dirtier */
>> +#endif
>>  } __attribute__((aligned(sizeof(long))));
>>       /*
>>        * On most architectures that alignment is already the case; but
>> @@ -652,6 +655,12 @@ struct address_space {
>>        * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
>>        */
>>
>> +/*
>> + * When an address_space is shared by multiple memcg dirtieres, then i_memcg is
>> + * set to this special, wildcard, css_id value (zero).
>> + */
>> +#define I_MEMCG_SHARED 0
>> +
>>  struct block_device {
>>       dev_t                   bd_dev;  /* not a kdev_t - it's a search key */
>>       int                     bd_openers;
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 77e47f5..14b6d67 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -103,6 +103,8 @@ mem_cgroup_prepare_migration(struct page *page,
>>  extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
>>       struct page *oldpage, struct page *newpage, bool migration_ok);
>>
>> +void mem_cgroup_mark_inode_dirty(struct inode *inode);
>> +
>>  /*
>>   * For memory reclaim.
>>   */
>> @@ -273,6 +275,10 @@ static inline void mem_cgroup_end_migration(struct mem_cgroup *mem,
>>  {
>>  }
>>
>> +static inline void mem_cgroup_mark_inode_dirty(struct inode *inode)
>> +{
>> +}
>> +
>>  static inline int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem)
>>  {
>>       return 0;
>> diff --git a/include/trace/events/memcontrol.h b/include/trace/events/memcontrol.h
>> new file mode 100644
>> index 0000000..781ef9fc
>> --- /dev/null
>> +++ b/include/trace/events/memcontrol.h
>> @@ -0,0 +1,32 @@
>> +#undef TRACE_SYSTEM
>> +#define TRACE_SYSTEM memcontrol
>> +
>> +#if !defined(_TRACE_MEMCONTROL_H) || defined(TRACE_HEADER_MULTI_READ)
>> +#define _TRACE_MEMCONTROL_H
>> +
>> +#include <linux/types.h>
>> +#include <linux/tracepoint.h>
>> +
>> +TRACE_EVENT(mem_cgroup_mark_inode_dirty,
>> +     TP_PROTO(struct inode *inode),
>> +
>> +     TP_ARGS(inode),
>> +
>> +     TP_STRUCT__entry(
>> +             __field(unsigned long, ino)
>> +             __field(unsigned short, css_id)
>> +             ),
>> +
>> +     TP_fast_assign(
>> +             __entry->ino = inode->i_ino;
>> +             __entry->css_id =
>> +                     inode->i_mapping ? inode->i_mapping->i_memcg : 0;
>> +             ),
>> +
>> +     TP_printk("ino=%ld css_id=%d", __entry->ino, __entry->css_id)
>> +)
>> +
>> +#endif /* _TRACE_MEMCONTROL_H */
>> +
>> +/* This part must be outside protection */
>> +#include <trace/define_trace.h>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index bf642b5..e83ef74 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -54,6 +54,9 @@
>>
>>  #include <trace/events/vmscan.h>
>>
>> +#define CREATE_TRACE_POINTS
>> +#include <trace/events/memcontrol.h>
>> +
>>  struct cgroup_subsys mem_cgroup_subsys __read_mostly;
>>  #define MEM_CGROUP_RECLAIM_RETRIES   5
>>  struct mem_cgroup *root_mem_cgroup __read_mostly;
>> @@ -1122,6 +1125,27 @@ static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_
>>       return inactive_ratio;
>>  }
>>
>> +/*
>> + * Mark the current task's memcg as the memcg associated with inode.  Note: the
>> + * recorded cgroup css_id is not guaranteed to remain correct.  The current task
>> + * may be moved to another cgroup.  The memcg may also be deleted before the
>> + * caller has time to use the i_memcg.
>> + */
>> +void mem_cgroup_mark_inode_dirty(struct inode *inode)
>> +{
>> +     struct mem_cgroup *mem;
>> +     unsigned short id;
>> +
>> +     rcu_read_lock();
>> +     mem = mem_cgroup_from_task(current);
>> +     id = mem ? css_id(&mem->css) : 0;
>
> Ditto.

I agree, I_MEMCG_SHARED should be used instead of 0.

>> +     rcu_read_unlock();
>> +
>> +     inode->i_mapping->i_memcg = id;
>> +
>> +     trace_mem_cgroup_mark_inode_dirty(inode);
>> +}
>> +
>>  int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
>>  {
>>       unsigned long active;
>> --
>> 1.7.3.1
>
> Thanks,
> -Andrea
>