On 2016/5/6 1:09, Laura Abbott wrote:
> On 05/04/2016 08:27 PM, Chen Feng wrote:
>> Makes the ion buffer always alloced from page pool, no matter
>> it's cached or not. In this way, it can improve the efficiency
>> of it.
>>
>> Currently, there is no difference from cached or non-cached buffer
>> for the page pool.
>
>
> The advantage of the uncached pool was that the pages in the pool
> were always clean in the cache. This is lost here with the addition
> of cached pages to the same pool as uncached pages I agree the
> cache path could benefit from pooling but we need to keep the caching
> model consistent.
>
Yes, the buffer in the pool is non-cached.
I found that the ion don't have a invalid cache ops.
Currently, we use ioctl to keep the cache coherency.
In this way, there is no difference between these.
So, how do you think add a new cached pool in the system heap?
If yes, I can file a new patch to do this.
>>
>> Signed-off-by: Chen Feng <puck.chen@xxxxxxxxxxxxx>
>> ---
>> drivers/staging/android/ion/ion_system_heap.c | 19 ++-----------------
>> 1 file changed, 2 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
>> index b69dfc7..caf11fc 100644
>> --- a/drivers/staging/android/ion/ion_system_heap.c
>> +++ b/drivers/staging/android/ion/ion_system_heap.c
>> @@ -56,24 +56,10 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
>> struct ion_buffer *buffer,
>> unsigned long order)
>> {
>> - bool cached = ion_buffer_cached(buffer);
>> struct ion_page_pool *pool = heap->pools[order_to_index(order)];
>> 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);
>> - }
>> -
>> + page = ion_page_pool_alloc(pool);
>> return page;
>> }
>>
>> @@ -81,9 +67,8 @@ static void free_buffer_page(struct ion_system_heap *heap,
>> struct ion_buffer *buffer, struct page *page)
>> {
>> unsigned int order = compound_order(page);
>> - bool cached = ion_buffer_cached(buffer);
>>
>> - if (!cached && !(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)) {
>> + if (!(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)) {
>> struct ion_page_pool *pool = heap->pools[order_to_index(order)];
>>
>> ion_page_pool_free(pool, page);
>>
>
>
> .
>
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