2012/10/29 Minchan Kim <minchan@xxxxxxxxxx>:
> On Mon, Oct 29, 2012 at 04:12:55AM +0900, Joonsoo Kim wrote:
>> In current code, after flush_all_zero_pkmaps() is invoked,
>> then re-iterate all pkmaps. It can be optimized if flush_all_zero_pkmaps()
>> return index of flushed entry. With this index,
>> we can immediately map highmem page to virtual address represented by index.
>> So change return type of flush_all_zero_pkmaps()
>> and return index of last flushed entry.
>>
>> Signed-off-by: Joonsoo Kim <js1304@xxxxxxxxx>
>>
>> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
>> index ef788b5..0683869 100644
>> --- a/include/linux/highmem.h
>> +++ b/include/linux/highmem.h
>> @@ -32,6 +32,7 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
>>
>> #ifdef CONFIG_HIGHMEM
>> #include <asm/highmem.h>
>> +#define PKMAP_INDEX_INVAL (-1)
>
> How about this?
>
> #define PKMAP_INVALID_INDEX (-1)
Okay.
>>
>> /* declarations for linux/mm/highmem.c */
>> unsigned int nr_free_highpages(void);
>> diff --git a/mm/highmem.c b/mm/highmem.c
>> index 731cf9a..65beb9a 100644
>> --- a/mm/highmem.c
>> +++ b/mm/highmem.c
>> @@ -106,10 +106,10 @@ struct page *kmap_to_page(void *vaddr)
>> return virt_to_page(addr);
>> }
>>
>> -static void flush_all_zero_pkmaps(void)
>> +static int flush_all_zero_pkmaps(void)
>> {
>> int i;
>> - int need_flush = 0;
>> + int index = PKMAP_INDEX_INVAL;
>>
>> flush_cache_kmaps();
>>
>> @@ -141,10 +141,12 @@ static void flush_all_zero_pkmaps(void)
>> &pkmap_page_table[i]);
>>
>> set_page_address(page, NULL);
>> - need_flush = 1;
>> + index = i;
>
> How about returning first free index instead of last one?
> and update last_pkmap_nr to it.
Okay. It will be more good.
Thanks.
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