Re: [PATCH v1] ION: Sys_heap: Add cached pool to spead up cached buffer alloc

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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
> 
> 
> .
> 

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