Re: [PATCH] mm: hide per-cpu lists in output of show_mem()

[Konstantin Khlebnikov]

On Tue, Feb 24, 2015 at 11:41 PM, David Rientjes <rientjes@xxxxxxxxxx> wrote:
> On Fri, 20 Feb 2015, Konstantin Khlebnikov wrote:
>
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index 028565a..0538de0 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -1126,6 +1126,7 @@ extern void pagefault_out_of_memory(void);
>>   * various contexts.
>>   */
>>  #define SHOW_MEM_FILTER_NODES                (0x0001u)       /* disallowed nodes */
>> +#define SHOW_MEM_PERCPU_LISTS                (0x0002u)       /* per-zone per-cpu */
>>
>>  extern void show_free_areas(unsigned int flags);
>>  extern bool skip_free_areas_node(unsigned int flags, int nid);
>
> I, like others, think this should probably be left out until someone
> actually needs to use it.

Not a problem, this is just a few lines of code. We can get rid of it
at any time.

>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index a47f0b2..e591f3b 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -3198,20 +3198,29 @@ static void show_migration_types(unsigned char type)
>>   */
>>  void show_free_areas(unsigned int filter)
>>  {
>> +     unsigned long free_pcp = 0;
>>       int cpu;
>>       struct zone *zone;
>>
>>       for_each_populated_zone(zone) {
>>               if (skip_free_areas_node(filter, zone_to_nid(zone)))
>>                       continue;
>> -             show_node(zone);
>> -             printk("%s per-cpu:\n", zone->name);
>> +
>> +             if (filter & SHOW_MEM_PERCPU_LISTS) {
>> +                     show_node(zone);
>> +                     printk("%s per-cpu:\n", zone->name);
>> +             }
>>
>>               for_each_online_cpu(cpu) {
>>                       struct per_cpu_pageset *pageset;
>>
>>                       pageset = per_cpu_ptr(zone->pageset, cpu);
>>
>> +                     free_pcp += pageset->pcp.count;
>> +
>> +                     if (!(filter & SHOW_MEM_PERCPU_LISTS))
>> +                             continue;
>> +
>>                       printk("CPU %4d: hi:%5d, btch:%4d usd:%4d\n",
>>                              cpu, pageset->pcp.high,
>>                              pageset->pcp.batch, pageset->pcp.count);
>> @@ -3220,11 +3229,10 @@ void show_free_areas(unsigned int filter)
>>
>>       printk("active_anon:%lu inactive_anon:%lu isolated_anon:%lu\n"
>>               " active_file:%lu inactive_file:%lu isolated_file:%lu\n"
>> -             " unevictable:%lu"
>> -             " dirty:%lu writeback:%lu unstable:%lu\n"
>> -             " free:%lu slab_reclaimable:%lu slab_unreclaimable:%lu\n"
>> +             " unevictable:%lu dirty:%lu writeback:%lu unstable:%lu\n"
>> +             " slab_reclaimable:%lu slab_unreclaimable:%lu\n"
>>               " mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
>> -             " free_cma:%lu\n",
>> +             " free:%lu free_pcp:%lu free_cma:%lu\n",
>
> Why is "free:" itself moved?  It is unlikely, but I could imagine that
> this might break something that is parsing the kernel log and it would be
> better to just leave it where it is and add "free_pcp:" after "free_cma:"
> since this is extending the message.

I think it looks better at the beginning of new line, like this:

[   44.452955] Mem-Info:
[   44.453233] active_anon:2307 inactive_anon:36 isolated_anon:0
[   44.453233]  active_file:4120 inactive_file:4623 isolated_file:0
[   44.453233]  unevictable:0 dirty:6 writeback:0 unstable:0
[   44.453233]  slab_reclaimable:3500 slab_unreclaimable:7441
[   44.453233]  mapped:2113 shmem:45 pagetables:292 bounce:0
[   44.453233]  free:456891 free_pcp:12179 free_cma:0

In this order fields at each line have something in common.

I'll spend some some time playing with this code and oom log,
maybe I'll try to turn whole output into table or something.

>
>>               global_page_state(NR_ACTIVE_ANON),
>>               global_page_state(NR_INACTIVE_ANON),
>>               global_page_state(NR_ISOLATED_ANON),
>> @@ -3235,13 +3243,14 @@ void show_free_areas(unsigned int filter)
>>               global_page_state(NR_FILE_DIRTY),
>>               global_page_state(NR_WRITEBACK),
>>               global_page_state(NR_UNSTABLE_NFS),
>> -             global_page_state(NR_FREE_PAGES),
>>               global_page_state(NR_SLAB_RECLAIMABLE),
>>               global_page_state(NR_SLAB_UNRECLAIMABLE),
>>               global_page_state(NR_FILE_MAPPED),
>>               global_page_state(NR_SHMEM),
>>               global_page_state(NR_PAGETABLE),
>>               global_page_state(NR_BOUNCE),
>> +             global_page_state(NR_FREE_PAGES),
>> +             free_pcp,
>>               global_page_state(NR_FREE_CMA_PAGES));
>>
>>       for_each_populated_zone(zone) {
>> @@ -3249,6 +3258,11 @@ void show_free_areas(unsigned int filter)
>>
>>               if (skip_free_areas_node(filter, zone_to_nid(zone)))
>>                       continue;
>> +
>> +             free_pcp = 0;
>> +             for_each_online_cpu(cpu)
>> +                     free_pcp += per_cpu_ptr(zone->pageset, cpu)->pcp.count;
>> +
>>               show_node(zone);
>>               printk("%s"
>>                       " free:%lukB"
>> @@ -3275,6 +3289,8 @@ void show_free_areas(unsigned int filter)
>>                       " pagetables:%lukB"
>>                       " unstable:%lukB"
>>                       " bounce:%lukB"
>> +                     " free_pcp:%lukB"
>> +                     " local_pcp:%ukB"
>>                       " free_cma:%lukB"
>>                       " writeback_tmp:%lukB"
>>                       " pages_scanned:%lu"
>> @@ -3306,6 +3322,8 @@ void show_free_areas(unsigned int filter)
>>                       K(zone_page_state(zone, NR_PAGETABLE)),
>>                       K(zone_page_state(zone, NR_UNSTABLE_NFS)),
>>                       K(zone_page_state(zone, NR_BOUNCE)),
>> +                     K(free_pcp),
>> +                     K(this_cpu_read(zone->pageset->pcp.count)),
>>                       K(zone_page_state(zone, NR_FREE_CMA_PAGES)),
>>                       K(zone_page_state(zone, NR_WRITEBACK_TEMP)),
>>                       K(zone_page_state(zone, NR_PAGES_SCANNED)),
>>
>
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