Re: [PATCH 1/2] mm: Change the call sites of numa statistics items

[kemi <kemi.wang@intel.com>]

On 2017a1'08ae??15ae?JPY 17:49, Mel Gorman wrote:
> On Tue, Aug 15, 2017 at 04:45:35PM +0800, Kemi Wang wrote:
>> In this patch,  NUMA statistics is separated from zone statistics
>> framework, all the call sites of NUMA stats are changed to use
>> numa-stats-specific functions, it does not have any functionality change
>> except that the value of NUMA stats is shown behind zone page stats, and
>> the threshold size of NUMA stats is shown behind pcp threshold when users
>> *read* the zone info.
>>
>> E.g. cat /proc/zoneinfo
>>     ***Base***                           ***With this patch***
>> nr_free_pages 3976                         nr_free_pages 3976
>> nr_zone_inactive_anon 0                    nr_zone_inactive_anon 0
>> nr_zone_active_anon 0                      nr_zone_active_anon 0
>> nr_zone_inactive_file 0                    nr_zone_inactive_file 0
>> nr_zone_active_file 0                      nr_zone_active_file 0
>> nr_zone_unevictable 0                      nr_zone_unevictable 0
>> nr_zone_write_pending 0                    nr_zone_write_pending 0
>> nr_mlock     0                             nr_mlock     0
>> nr_page_table_pages 0                      nr_page_table_pages 0
>> nr_kernel_stack 0                          nr_kernel_stack 0
>> nr_bounce    0                             nr_bounce    0
>> nr_zspages   0                             nr_zspages   0
>> numa_hit 0                                *nr_free_cma  0*
>> numa_miss 0                                numa_hit     0
>> numa_foreign 0                             numa_miss    0
>> numa_interleave 0                          numa_foreign 0
>> numa_local   0                             numa_interleave 0
>> numa_other   0                             numa_local   0
>> *nr_free_cma 0*                            numa_other 0
>>     ...                                        ...
>> vm stats threshold: 10                     vm stats threshold: 10
>>     ...                                   *vm numa stats threshold: 10*
>>                                                ...
>>
>> The next patch updates the numa stats counter size and threshold.
>>
>> Signed-off-by: Kemi Wang <kemi.wang@intel.com>
>> ---
>>  drivers/base/node.c    |  22 ++++---
>>  include/linux/mmzone.h |  25 +++++---
>>  include/linux/vmstat.h |  29 +++++++++
>>  mm/page_alloc.c        |  10 +--
>>  mm/vmstat.c            | 167 +++++++++++++++++++++++++++++++++++++++++++++++--
>>  5 files changed, 227 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/base/node.c b/drivers/base/node.c
>> index d8dc830..12080c6 100644
>> --- a/drivers/base/node.c
>> +++ b/drivers/base/node.c
>> @@ -160,12 +160,12 @@ static ssize_t node_read_numastat(struct device *dev,
>>  		       "interleave_hit %lu\n"
>>  		       "local_node %lu\n"
>>  		       "other_node %lu\n",
>> -		       sum_zone_node_page_state(dev->id, NUMA_HIT),
>> -		       sum_zone_node_page_state(dev->id, NUMA_MISS),
>> -		       sum_zone_node_page_state(dev->id, NUMA_FOREIGN),
>> -		       sum_zone_node_page_state(dev->id, NUMA_INTERLEAVE_HIT),
>> -		       sum_zone_node_page_state(dev->id, NUMA_LOCAL),
>> -		       sum_zone_node_page_state(dev->id, NUMA_OTHER));
>> +		       sum_zone_node_numa_state(dev->id, NUMA_HIT),
>> +		       sum_zone_node_numa_state(dev->id, NUMA_MISS),
>> +		       sum_zone_node_numa_state(dev->id, NUMA_FOREIGN),
>> +		       sum_zone_node_numa_state(dev->id, NUMA_INTERLEAVE_HIT),
>> +		       sum_zone_node_numa_state(dev->id, NUMA_LOCAL),
>> +		       sum_zone_node_numa_state(dev->id, NUMA_OTHER));
>>  }
> 
> The names are very similar and it would be preferred if the names were
> visually different like sum_zone_numa_stat() which is hard to confuse with
> the zone stat fields.
> 
Agree. Thanks for your suggestion.

>>  static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
>>  
>> @@ -181,9 +181,17 @@ static ssize_t node_read_vmstat(struct device *dev,
>>  		n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
>>  			     sum_zone_node_page_state(nid, i));
>>  
>> -	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
>> +#ifdef CONFIG_NUMA
>> +	for (i = 0; i < NR_VM_ZONE_NUMA_STAT_ITEMS; i++)
>>  		n += sprintf(buf+n, "%s %lu\n",
>>  			     vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
>> +			     sum_zone_node_numa_state(nid, i));
>> +#endif
> 
> Similar with NR_VM_ZONE_NUMA_STAT_ITEMS, it's too similar to
> NR_VM_NODE_STAT_ITEMS>
How about NR_VM_NUMA_STAT_ITEMS? anyone has better idea?
 
>> +
>> +	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
>> +		n += sprintf(buf+n, "%s %lu\n",
>> +			     vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
>> +			     NR_VM_ZONE_NUMA_STAT_ITEMS],
>>  			     node_page_state(pgdat, i));
>>  
>>  	return n;
>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>> index fc14b8b..0b11ba7 100644
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -114,6 +114,20 @@ struct zone_padding {
>>  #define ZONE_PADDING(name)
>>  #endif
>>  
>> +#ifdef CONFIG_NUMA
>> +enum zone_numa_stat_item {
>> +	NUMA_HIT,		/* allocated in intended node */
>> +	NUMA_MISS,		/* allocated in non intended node */
>> +	NUMA_FOREIGN,		/* was intended here, hit elsewhere */
>> +	NUMA_INTERLEAVE_HIT,	/* interleaver preferred this zone */
>> +	NUMA_LOCAL,		/* allocation from local node */
>> +	NUMA_OTHER,		/* allocation from other node */
>> +	NR_VM_ZONE_NUMA_STAT_ITEMS
>> +};
>> +#else
>> +#define NR_VM_ZONE_NUMA_STAT_ITEMS 0
>> +#endif
>> +
>>  enum zone_stat_item {
>>  	/* First 128 byte cacheline (assuming 64 bit words) */
>>  	NR_FREE_PAGES,
>> @@ -132,14 +146,6 @@ enum zone_stat_item {
>>  #if IS_ENABLED(CONFIG_ZSMALLOC)
>>  	NR_ZSPAGES,		/* allocated in zsmalloc */
>>  #endif
>> -#ifdef CONFIG_NUMA
>> -	NUMA_HIT,		/* allocated in intended node */
>> -	NUMA_MISS,		/* allocated in non intended node */
>> -	NUMA_FOREIGN,		/* was intended here, hit elsewhere */
>> -	NUMA_INTERLEAVE_HIT,	/* interleaver preferred this zone */
>> -	NUMA_LOCAL,		/* allocation from local node */
>> -	NUMA_OTHER,		/* allocation from other node */
>> -#endif
>>  	NR_FREE_CMA_PAGES,
>>  	NR_VM_ZONE_STAT_ITEMS };
>>  
>> @@ -276,6 +282,8 @@ struct per_cpu_pageset {
>>  	struct per_cpu_pages pcp;
>>  #ifdef CONFIG_NUMA
>>  	s8 expire;
>> +	s8 numa_stat_threshold;
>> +	s8 vm_numa_stat_diff[NR_VM_ZONE_NUMA_STAT_ITEMS];
>>  #endif
>>  #ifdef CONFIG_SMP
>>  	s8 stat_threshold;
> 
> Ok. this slightly increases the size of the per_cpu_pageset due to
> numa_stat_threshold. The structure occupes 2 cache lines and still occupies
> 2 cache lines afterwards so that is ok but consider hard-coding the value
> of it. The locality stats are never used as part of a decision made by the
> kernel and they get summed when reading proc unconditionally. There is little
> benefit to tuning that threshold at all and there should be a very small
> performance gain if it's removed because it'll be a compile-time constant.
> 
Agree, Thanks. I will remove numa_stat_threshold in next version.

> The rest of the patch is mostly mechanical.
> 

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