Re: [PATCH] mm: Use unsigned types for fragmentation score

From: Nitin Gupta
Date: Thu Jun 18 2020 - 10:25:05 EST


On 6/18/20 6:41 AM, Baoquan He wrote:
> On 06/17/20 at 06:03pm, Nitin Gupta wrote:
>> Proactive compaction uses per-node/zone "fragmentation score" which
>> is always in range [0, 100], so use unsigned type of these scores
>> as well as for related constants.
>>
>> Signed-off-by: Nitin Gupta <nigupta@xxxxxxxxxx>
>> ---
>> include/linux/compaction.h | 4 ++--
>> kernel/sysctl.c | 2 +-
>> mm/compaction.c | 18 +++++++++---------
>> mm/vmstat.c | 2 +-
>> 4 files changed, 13 insertions(+), 13 deletions(-)
>>
>> diff --git a/include/linux/compaction.h b/include/linux/compaction.h
>> index 7a242d46454e..25a521d299c1 100644
>> --- a/include/linux/compaction.h
>> +++ b/include/linux/compaction.h
>> @@ -85,13 +85,13 @@ static inline unsigned long compact_gap(unsigned int order)
>>
>> #ifdef CONFIG_COMPACTION
>> extern int sysctl_compact_memory;
>> -extern int sysctl_compaction_proactiveness;
>> +extern unsigned int sysctl_compaction_proactiveness;
>> extern int sysctl_compaction_handler(struct ctl_table *table, int write,
>> void *buffer, size_t *length, loff_t *ppos);
>> extern int sysctl_extfrag_threshold;
>> extern int sysctl_compact_unevictable_allowed;
>>
>> -extern int extfrag_for_order(struct zone *zone, unsigned int order);
>> +extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
>> extern int fragmentation_index(struct zone *zone, unsigned int order);
>> extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
>> unsigned int order, unsigned int alloc_flags,
>> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
>> index 58b0a59c9769..40180cdde486 100644
>> --- a/kernel/sysctl.c
>> +++ b/kernel/sysctl.c
>> @@ -2833,7 +2833,7 @@ static struct ctl_table vm_table[] = {
>> {
>> .procname = "compaction_proactiveness",
>> .data = &sysctl_compaction_proactiveness,
>> - .maxlen = sizeof(int),
>> + .maxlen = sizeof(sysctl_compaction_proactiveness),
>
> Patch looks good to me. Wondering why not using 'unsigned int' here,
> just curious.
>


It's just coding style preference. I see the same style used for many
other sysctls too (min_free_kbytes etc.).

Thanks,
Nitin