Hello Suanming
Please find my comments below. However please note that so far I have
never used DPDK bitmaps so I might not be the best person to comment -
this patch needs some attention so I spent some time on it.
Overall I'm fine with the changes however since this is a performance
enhancement I've added some remarks/comments.
On 3/10/20 9:21 AM, Suanming Mou wrote:
> Currently, in the case to use bitmap as resource allocator, after
> bitmap creation, all the bitmap bits should be set to indicate the
> bit available. Every time when allocate one bit, search for the set
> bits and clear it to make it in use.
>
> Add a new rte_bitmap_init_with_all_set() function to have a quick
> fill up the bitmap bits.
>
> Comparing with the case create the bitmap as empty and set the bitmap
> one by one, the new function costs less cycles.
>
> Signed-off-by: Suanming Mou <suanmi...@mellanox.com>
> ---
> lib/librte_eal/common/include/rte_bitmap.h | 32
> ++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/lib/librte_eal/common/include/rte_bitmap.h
> b/lib/librte_eal/common/include/rte_bitmap.h
> index 6b846f2..36b32e4 100644
> --- a/lib/librte_eal/common/include/rte_bitmap.h
> +++ b/lib/librte_eal/common/include/rte_bitmap.h
> @@ -483,6 +483,38 @@ struct rte_bitmap {
> return 0;
> }
>
> +/**
> + * Bitmap initialization with all bits set
> + *
> + * @param n_bits
> + * Number of pre-allocated bits in array2.
> + * @param mem
> + * Base address of array1 and array2.
> + * @param mem_size
> + * Minimum expected size of bitmap.
> + * @return
> + * Handle to bitmap instance.
> + */
> +static inline struct rte_bitmap *
> +rte_bitmap_init_with_all_set(uint32_t n_bits, uint8_t *mem, uint32_t
> mem_size)
> +{
> + uint32_t i;
> + uint32_t slabs = n_bits / RTE_BITMAP_SLAB_BIT_SIZE;
> + struct rte_bitmap *bmp = rte_bitmap_init(n_bits, mem, mem_size);
> +
> + if (!bmp)
> + return NULL;
> + /* Fill the arry2 byte aligned bits. */
> + memset(bmp->array2, 0xff, slabs * sizeof(bmp->array2[0]));
In rte_bitmap_init() we clear memory with 0 and now we set it with 1s.
Maybe separating the configuration from the actual initialization would
be better? So that you call __rte_bitmap_init() and later zero in
rte_bitmap_init() and set to 1s here.
> + /* Fill the arry1 bits. */
> + for (i = 0; i < n_bits; i += RTE_BITMAP_CL_BIT_SIZE)
> + rte_bitmap_set(bmp, i);
Maybe you could here also compute the number of array1 bytes that can be
set to FF and use memset() and for the remaining user rte_bitmap_set()?
Right now you are also touching array2 memory which was already set above.
> + /* Fill the arry2 left not byte aligned bits. */
> + for (i = slabs * RTE_BITMAP_SLAB_BIT_SIZE; i < n_bits; i++)
> + rte_bitmap_set(bmp, i);
> + return bmp;
> +}
> +
With regards
Andrzej Ostruszka
