Hi Laura,
On 2016/5/10 7:50, Laura Abbott wrote:
> On 05/09/2016 01:37 AM, Chen Feng wrote:
>> Add ion cached pool in system heap.
>>
>> Signed-off-by: Chen Feng <puck.chen@xxxxxxxxxxxxx>
>> Signed-off-by: Xia Qing <saberlily.xia@xxxxxxxxxxxxx>
>> Reviewed-by: Fu Jun <oliver.fu@xxxxxxxxxxxxx>
>> ---
>> drivers/staging/android/ion/ion_system_heap.c | 145 +++++++++++++++++---------
>> 1 file changed, 95 insertions(+), 50 deletions(-)
>>
>> diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
>> index b69dfc7..c633252 100644
>> --- a/drivers/staging/android/ion/ion_system_heap.c
>> +++ b/drivers/staging/android/ion/ion_system_heap.c
>> @@ -49,7 +49,8 @@ static inline unsigned int order_to_size(int order)
>>
>> struct ion_system_heap {
>> struct ion_heap heap;
>> - struct ion_page_pool *pools[0];
>> + struct ion_page_pool *uncached_pools[0];
>> + struct ion_page_pool *cached_pools[0];
>> };
>>
>> static struct page *alloc_buffer_page(struct ion_system_heap *heap,
>> @@ -57,39 +58,36 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
>> unsigned long order)
>> {
>> bool cached = ion_buffer_cached(buffer);
>> - struct ion_page_pool *pool = heap->pools[order_to_index(order)];
>> + struct ion_page_pool *pool;
>> struct page *page;
>>
>> - if (!cached) {
>> - page = ion_page_pool_alloc(pool);
>> - } else {
>> - gfp_t gfp_flags = low_order_gfp_flags;
>> -
>> - if (order > 4)
>> - gfp_flags = high_order_gfp_flags;
>> - page = alloc_pages(gfp_flags | __GFP_COMP, order);
>> - if (!page)
>> - return NULL;
>> - ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
>> - DMA_BIDIRECTIONAL);
>> - }
>> + if (!cached)
>> + pool = heap->uncached_pools[order_to_index(order)];
>> + else
>> + pool = heap->cached_pools[order_to_index(order)];
>>
>> + page = ion_page_pool_alloc(pool);
>> return page;
>> }
>>
>
> This is a change in behavior. The page is no longer guaranteed to be synced
> in the cache. If the page came from the pool (not just freshly allocated)
> the cache state is unknown. Do you have a good explanation why we no longer
> need to do the cache flush here on every allocation?
>
Yes, no more explanation here.
Please see my v1[1] version.
Thanks for review!
[1] http://thread.gmane.org/gmane.linux.kernel/2217505
> Thanks,
> Laura
>
> .
>
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