[PATCH 0/3] Cleanup for vmstat

[PATCH 0/3] Cleanup for vmstat

[Miaohe Lin]

Hi all,
This series contains cleanups to remove unneeded return value, correct
wrong comment and simplify the array size calculation. More details can
be found in the respective changelogs. Thanks!

Miaohe Lin (3):
  mm/vmstat: correct some wrong comments
  mm/vmstat: simplify the array size calculation
  mm/vmstat: remove unneeded return value

 mm/vmstat.c | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

-- 
2.23.0

[PATCH 1/3] mm/vmstat: correct some wrong comments

[Miaohe Lin]

Correct wrong fls(mem+1) to fls(mem)+1 and remove the duplicated
comment with quiet_vmstat().

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/vmstat.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index b0534e068166..57e8e7fda7aa 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -204,7 +204,7 @@ int calculate_normal_threshold(struct zone *zone)
 	 *
 	 * Some sample thresholds:
 	 *
-	 * Threshold	Processors	(fls)	Zonesize	fls(mem+1)
+	 * Threshold	Processors	(fls)	Zonesize	fls(mem)+1
 	 * ------------------------------------------------------------------
 	 * 8		1		1	0.9-1 GB	4
 	 * 16		2		2	0.9-1 GB	4
@@ -1873,11 +1873,6 @@ static void vmstat_update(struct work_struct *w)
 	}
 }
 
-/*
- * Switch off vmstat processing and then fold all the remaining differentials
- * until the diffs stay at zero. The function is used by NOHZ and can only be
- * invoked when tick processing is not active.
- */
 /*
  * Check if the diffs for a certain cpu indicate that
  * an update is needed.
-- 
2.23.0

[PATCH 2/3] mm/vmstat: simplify the array size calculation

[Miaohe Lin]

We can replace the array_num * sizeof(array[0]) with sizeof(array) to
simplify the code.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/vmstat.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 57e8e7fda7aa..76aef9510f6d 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1889,17 +1889,15 @@ static bool need_update(int cpu)
 		/*
 		 * The fast way of checking if there are any vmstat diffs.
 		 */
-		if (memchr_inv(pzstats->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS *
-			       sizeof(pzstats->vm_stat_diff[0])))
+		if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff)))
 			return true;
 
 		if (last_pgdat == zone->zone_pgdat)
 			continue;
 		last_pgdat = zone->zone_pgdat;
 		n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu);
-		if (memchr_inv(n->vm_node_stat_diff, 0, NR_VM_NODE_STAT_ITEMS *
-			       sizeof(n->vm_node_stat_diff[0])))
-		    return true;
+		if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff)))
+			return true;
 	}
 	return false;
 }
-- 
2.23.0

[PATCH 3/3] mm/vmstat: remove unneeded return value

[Miaohe Lin]

The return value of pagetypeinfo_showfree and pagetypeinfo_showblockcount
are unused now. Remove them.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/vmstat.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76aef9510f6d..6246bab9fae2 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1452,7 +1452,7 @@ static void pagetypeinfo_showfree_print(struct seq_file *m,
 }
 
 /* Print out the free pages at each order for each migatetype */
-static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
+static void pagetypeinfo_showfree(struct seq_file *m, void *arg)
 {
 	int order;
 	pg_data_t *pgdat = (pg_data_t *)arg;
@@ -1464,8 +1464,6 @@ static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 	seq_putc(m, '\n');
 
 	walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
-
-	return 0;
 }
 
 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
@@ -1501,7 +1499,7 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 }
 
 /* Print out the number of pageblocks for each migratetype */
-static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
+static void pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 {
 	int mtype;
 	pg_data_t *pgdat = (pg_data_t *)arg;
@@ -1512,8 +1510,6 @@ static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 	seq_putc(m, '\n');
 	walk_zones_in_node(m, pgdat, true, false,
 		pagetypeinfo_showblockcount_print);
-
-	return 0;
 }
 
 /*
-- 
2.23.0

Re: [PATCH 2/3] mm/vmstat: simplify the array size calculation

[David Hildenbrand]

On 15.07.21 14:29, Miaohe Lin wrote:
> We can replace the array_num * sizeof(array[0]) with sizeof(array) to
> simplify the code.

Could have mentioned taht your fixing indentation of one "return true;"

LGTM

Reviewed-by: David Hildenbrand <david@redhat.com>

> 
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>   mm/vmstat.c | 8 +++-----
>   1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 57e8e7fda7aa..76aef9510f6d 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1889,17 +1889,15 @@ static bool need_update(int cpu)
>   		/*
>   		 * The fast way of checking if there are any vmstat diffs.
>   		 */
> -		if (memchr_inv(pzstats->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS *
> -			       sizeof(pzstats->vm_stat_diff[0])))
> +		if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff)))
>   			return true;
>   
>   		if (last_pgdat == zone->zone_pgdat)
>   			continue;
>   		last_pgdat = zone->zone_pgdat;
>   		n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu);
> -		if (memchr_inv(n->vm_node_stat_diff, 0, NR_VM_NODE_STAT_ITEMS *
> -			       sizeof(n->vm_node_stat_diff[0])))
> -		    return true;
> +		if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff)))
> +			return true;
>   	}
>   	return false;
>   }
> 


-- 
Thanks,

David / dhildenb

Re: [PATCH 3/3] mm/vmstat: remove unneeded return value

[David Hildenbrand]

On 15.07.21 14:29, Miaohe Lin wrote:
> The return value of pagetypeinfo_showfree and pagetypeinfo_showblockcount
> are unused now. Remove them.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>   mm/vmstat.c | 8 ++------
>   1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 76aef9510f6d..6246bab9fae2 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1452,7 +1452,7 @@ static void pagetypeinfo_showfree_print(struct seq_file *m,
>   }
>   
>   /* Print out the free pages at each order for each migatetype */
> -static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
> +static void pagetypeinfo_showfree(struct seq_file *m, void *arg)
>   {
>   	int order;
>   	pg_data_t *pgdat = (pg_data_t *)arg;
> @@ -1464,8 +1464,6 @@ static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
>   	seq_putc(m, '\n');
>   
>   	walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
> -
> -	return 0;
>   }
>   
>   static void pagetypeinfo_showblockcount_print(struct seq_file *m,
> @@ -1501,7 +1499,7 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,
>   }
>   
>   /* Print out the number of pageblocks for each migratetype */
> -static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
> +static void pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
>   {
>   	int mtype;
>   	pg_data_t *pgdat = (pg_data_t *)arg;
> @@ -1512,8 +1510,6 @@ static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
>   	seq_putc(m, '\n');
>   	walk_zones_in_node(m, pgdat, true, false,
>   		pagetypeinfo_showblockcount_print);
> -
> -	return 0;
>   }
>   
>   /*
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

Re: [PATCH 2/3] mm/vmstat: simplify the array size calculation

[Miaohe Lin]

On 2021/7/16 20:58, David Hildenbrand wrote:
> On 15.07.21 14:29, Miaohe Lin wrote:
>> We can replace the array_num * sizeof(array[0]) with sizeof(array) to
>> simplify the code.
> 
> Could have mentioned taht your fixing indentation of one "return true;"
> 

Yes, but I thought that's too trivial to mention... I would pay attention to it later.

> LGTM
> 
> Reviewed-by: David Hildenbrand <david@redhat.com>

Many thanks for your review and reply!

> 
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>>   mm/vmstat.c | 8 +++-----
>>   1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/mm/vmstat.c b/mm/vmstat.c
>> index 57e8e7fda7aa..76aef9510f6d 100644
>> --- a/mm/vmstat.c
>> +++ b/mm/vmstat.c
>> @@ -1889,17 +1889,15 @@ static bool need_update(int cpu)
>>           /*
>>            * The fast way of checking if there are any vmstat diffs.
>>            */
>> -        if (memchr_inv(pzstats->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS *
>> -                   sizeof(pzstats->vm_stat_diff[0])))
>> +        if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff)))
>>               return true;
>>             if (last_pgdat == zone->zone_pgdat)
>>               continue;
>>           last_pgdat = zone->zone_pgdat;
>>           n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu);
>> -        if (memchr_inv(n->vm_node_stat_diff, 0, NR_VM_NODE_STAT_ITEMS *
>> -                   sizeof(n->vm_node_stat_diff[0])))
>> -            return true;
>> +        if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff)))
>> +            return true;
>>       }
>>       return false;
>>   }
>>
> 
>