Re: [PATCH v1] ION: Sys_heap: Add cached pool to spead up cached buffer alloc
From: Chen Feng
Date: Tue May 10 2016 - 22:33:48 EST
On 2016/5/11 6:48, Laura Abbott wrote:
> On 05/09/2016 04:35 AM, Chen Feng wrote:
>> Add ion cached pool in system heap. This patch add a cached pool
>> in system heap. It has a great improvement of alloc for cached
>> buffer.
>>
>
> Can you give some benchmark numbers here?
>
ok, My test is using iontest userspace.
I will share the result next version.
By the way, which benchmark you prefer to use for ION test?
>> v1: Makes the cached buffer zeroed before going to pool
>>
>> 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 | 155 +++++++++++++++++---------
>> 1 file changed, 103 insertions(+), 52 deletions(-)
>>
>> diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
>> index b69dfc7..4b14a0b 100644
>> --- a/drivers/staging/android/ion/ion_system_heap.c
>> +++ b/drivers/staging/android/ion/ion_system_heap.c
>> @@ -49,47 +49,55 @@ 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];
>> };
>>
>
>
> I don't think this is correct based on https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> and some discussions with others. Their tests showed this may just result in the
> two struct members aliasing, which is not what we want.
>
> The flexible array isn't really necessary here anyway. The number of orders we want
> is known at compile time and
>
Yes, change this latter.
> -static const int num_orders = ARRAY_SIZE(orders);
> +
> +#define NUM_ORDERS ARRAY_SIZE(orders)
> +
>
> should let the NUM_ORDERS be used as a constant initializer in the struct.
>
ok.
>> +/**
>> + * The page from page-pool are all zeroed before. We need do cache
>> + * clean for cached buffer. The uncached buffer are always non-cached
>> + * since it's allocated. So no need for non-cached pages.
>> + */
>> 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 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 (!cached)
>> + pool = heap->uncached_pools[order_to_index(order)];
>> + else
>> + pool = heap->cached_pools[order_to_index(order)];
>>
>> - 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);
>>
>> + if (cached)
>> + ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
>> + DMA_BIDIRECTIONAL);
>> return page;
>> }
>>
>
> This is doing an extra sync for newly allocated pages. If the buffer was
> just allocated the sync should be skipped.
>
Yes, if we want not to do this extra sync for newly allocated pages.
I will add a new parameter in the ion page-pool to distinguish from
it's cached or not.
>> static void free_buffer_page(struct ion_system_heap *heap,
>> struct ion_buffer *buffer, struct page *page)
>> {
>> + struct ion_page_pool *pool;
>> unsigned int order = compound_order(page);
>> bool cached = ion_buffer_cached(buffer);
>>
>> - if (!cached && !(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);
>> - } else {
>> + /* go to system */
>> + if (buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE) {
>> __free_pages(page, order);
>> + return;
>> }
>> +
>> + if (!cached)
>> + pool = heap->uncached_pools[order_to_index(order)];
>> + else
>> + pool = heap->cached_pools[order_to_index(order)];
>> +
>> + ion_page_pool_free(pool, page);
>> }
>>
>>
>> @@ -181,16 +189,11 @@ static void ion_system_heap_free(struct ion_buffer *buffer)
>> struct ion_system_heap,
>> heap);
>> struct sg_table *table = buffer->sg_table;
>> - bool cached = ion_buffer_cached(buffer);
>> struct scatterlist *sg;
>> int i;
>>
>> - /*
>> - * uncached pages come from the page pools, zero them before returning
>> - * for security purposes (other allocations are zerod at
>> - * alloc time
>> - */
>> - if (!cached && !(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE))
>> + /* zero the buffer before goto page pool */
>> + if (!(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE))
>> ion_heap_buffer_zero(buffer);
>>
>> for_each_sg(table->sgl, sg, table->nents, i)
>> @@ -224,19 +227,29 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
>> only_scan = 1;
>>
>> for (i = 0; i < num_orders; i++) {
>> - struct ion_page_pool *pool = sys_heap->pools[i];
>> -
>> - nr_freed = ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);
>> - nr_total += nr_freed;
>> + struct ion_page_pool *pool = sys_heap->uncached_pools[i];
>>
>> if (!only_scan) {
>> + nr_freed = ion_page_pool_shrink(pool, gfp_mask,
>> + nr_to_scan);
>> nr_to_scan -= nr_freed;
>> - /* shrink completed */
>> + nr_total += nr_freed;
>> + pool = sys_heap->cached_pools[i];
Here are some bugs, I will also modify here next version.
>> + nr_freed = ion_page_pool_shrink(pool, gfp_mask,
>> + nr_to_scan);
>> + nr_to_scan -= nr_freed;
>> + nr_total += nr_freed;
>> if (nr_to_scan <= 0)
>> break;
>> + } else {
>> + nr_freed = ion_page_pool_shrink(pool, gfp_mask,
>> + nr_to_scan);
>> + nr_total += nr_freed;
>> + nr_freed = ion_page_pool_shrink(pool, gfp_mask,
>> + nr_to_scan);
>> + nr_total += nr_freed;
>> }
>> }
>> -
>> return nr_total;
>> }
>>
>> @@ -259,27 +272,69 @@ static int ion_system_heap_debug_show(struct ion_heap *heap, struct seq_file *s,
>> struct ion_system_heap,
>> heap);
>> int i;
>> + struct ion_page_pool *pool;
>>
>> for (i = 0; i < num_orders; i++) {
>> - struct ion_page_pool *pool = sys_heap->pools[i];
>> + pool = sys_heap->uncached_pools[i];
>>
>> - seq_printf(s, "%d order %u highmem pages in pool = %lu total\n",
>> + seq_printf(s, "%d order %u highmem pages uncached %lu total\n",
>> pool->high_count, pool->order,
>> (PAGE_SIZE << pool->order) * pool->high_count);
>> - seq_printf(s, "%d order %u lowmem pages in pool = %lu total\n",
>> + seq_printf(s, "%d order %u lowmem pages uncached %lu total\n",
>> pool->low_count, pool->order,
>> (PAGE_SIZE << pool->order) * pool->low_count);
>> }
>> +
>> + for (i = 0; i < num_orders; i++) {
>> + pool = sys_heap->cached_pools[i];
>> +
>> + seq_printf(s, "%d order %u highmem pages cached %lu total\n",
>> + pool->high_count, pool->order,
>> + (PAGE_SIZE << pool->order) * pool->high_count);
>> + seq_printf(s, "%d order %u lowmem pages cached %lu total\n",
>> + pool->low_count, pool->order,
>> + (PAGE_SIZE << pool->order) * pool->low_count);
>> + }
>> + return 0;
>> +}
>> +
>> +static void ion_system_heap_destroy_pools(struct ion_page_pool **pools)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < num_orders; i++)
>> + if (pools[i])
>> + ion_page_pool_destroy(pools[i]);
>> +}
>> +
>> +static int ion_system_heap_create_pools(struct ion_page_pool **pools)
>> +{
>> + int i;
>> + gfp_t gfp_flags = low_order_gfp_flags;
>> +
>> + for (i = 0; i < num_orders; i++) {
>> + struct ion_page_pool *pool;
>> +
>> + if (orders[i] > 4)
>> + gfp_flags = high_order_gfp_flags;
>> +
>> + pool = ion_page_pool_create(gfp_flags, orders[i]);
>> + if (!pool)
>> + goto err_create_pool;
>> + pools[i] = pool;
>> + }
>> return 0;
>> +err_create_pool:
>> + ion_system_heap_destroy_pools(pools);
>> + return -ENOMEM;
>> }
>>
>> struct ion_heap *ion_system_heap_create(struct ion_platform_heap *unused)
>> {
>> struct ion_system_heap *heap;
>> - int i;
>>
>> heap = kzalloc(sizeof(struct ion_system_heap) +
>> - sizeof(struct ion_page_pool *) * num_orders,
>> + sizeof(struct ion_page_pool *) * num_orders * 2,
>> GFP_KERNEL);
>> if (!heap)
>> return ERR_PTR(-ENOMEM);
>> @@ -287,24 +342,18 @@ struct ion_heap *ion_system_heap_create(struct ion_platform_heap *unused)
>> heap->heap.type = ION_HEAP_TYPE_SYSTEM;
>> heap->heap.flags = ION_HEAP_FLAG_DEFER_FREE;
>>
>> - for (i = 0; i < num_orders; i++) {
>> - struct ion_page_pool *pool;
>> - gfp_t gfp_flags = low_order_gfp_flags;
>> + if (ion_system_heap_create_pools(heap->uncached_pools))
>> + goto free_heap;
>>
>> - if (orders[i] > 4)
>> - gfp_flags = high_order_gfp_flags;
>> - pool = ion_page_pool_create(gfp_flags, orders[i]);
>> - if (!pool)
>> - goto destroy_pools;
>> - heap->pools[i] = pool;
>> - }
>> + if (ion_system_heap_create_pools(heap->cached_pools))
>> + goto destroy_uncached_pools;
>>
>> heap->heap.debug_show = ion_system_heap_debug_show;
>> return &heap->heap;
>>
>> -destroy_pools:
>> - while (i--)
>> - ion_page_pool_destroy(heap->pools[i]);
>> +destroy_uncached_pools:
>> + ion_system_heap_destroy_pools(heap->uncached_pools);
>> +free_heap:
>> kfree(heap);
>> return ERR_PTR(-ENOMEM);
>> }
>> @@ -316,8 +365,10 @@ void ion_system_heap_destroy(struct ion_heap *heap)
>> heap);
>> int i;
>>
>> - for (i = 0; i < num_orders; i++)
>> - ion_page_pool_destroy(sys_heap->pools[i]);
>> + for (i = 0; i < num_orders; i++) {
>> + ion_page_pool_destroy(sys_heap->uncached_pools[i]);
>> + ion_page_pool_destroy(sys_heap->cached_pools[i]);
>> + }
>> kfree(sys_heap);
>> }
>>
>>
>
> Thanks,
> Laura
>
>
> .
>