On Tue, Aug 15, 2017 at 11:37:42AM +0530, Santosh Shukla wrote:
> Some mempool hw like octeontx/fpa block, demands block size
> (/total_elem_sz) aligned object start address.
>
> Introducing an MEMPOOL_F_POOL_BLK_SZ_ALIGNED flag.
> If this flag is set:
> - Align object start address to a multiple of total_elt_sz.
Please specify if it's virtual or physical address.
What do you think about MEMPOOL_F_BLK_ALIGNED_OBJECTS instead?
I don't really like BLK because the word "block" is not used anywhere
else in the mempool code. But I cannot find any good replacement for
it. If you have another idea, please suggest.
> - Allocate one additional object. Additional object is needed to make
> sure that requested 'n' object gets correctly populated. Example:
>
> - Let's say that we get 'x' size of memory chunk from memzone.
> - And application has requested 'n' object from mempool.
> - Ideally, we start using objects at start address 0 to...(x-block_sz)
> for n obj.
> - Not necessarily first object address i.e. 0 is aligned to block_sz.
> - So we derive 'offset' value for block_sz alignment purpose i.e..'off'.
> - That 'off' makes sure that start address of object is blk_sz
> aligned.
> - Calculating 'off' may end up sacrificing first block_sz area of
> memzone area x. So total number of the object which can fit in the
> pool area is n-1, Which is incorrect behavior.
>
> Therefore we request one additional object (/block_sz area) from memzone
> when F_BLK_SZ_ALIGNED flag is set.
>
> Signed-off-by: Santosh Shukla <santosh.shu...@caviumnetworks.com>
> Signed-off-by: Jerin Jacob <jerin.ja...@caviumnetworks.com>
> ---
> lib/librte_mempool/rte_mempool.c | 16 +++++++++++++---
> lib/librte_mempool/rte_mempool.h | 1 +
> 2 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_mempool/rte_mempool.c
> b/lib/librte_mempool/rte_mempool.c
> index 19e5e6ddf..7610f0d1f 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -239,10 +239,14 @@ rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t
> flags,
> */
> size_t
> rte_mempool_xmem_size(uint32_t elt_num, size_t total_elt_sz, uint32_t
> pg_shift,
> - __rte_unused const struct rte_mempool *mp)
> + const struct rte_mempool *mp)
> {
> size_t obj_per_page, pg_num, pg_sz;
>
> + if (mp && mp->flags & MEMPOOL_F_POOL_BLK_SZ_ALIGNED)
> + /* alignment need one additional object */
> + elt_num += 1;
> +
> if (total_elt_sz == 0)
> return 0;
I'm wondering if it's correct if the mempool area is not contiguous.
For instance:
page size = 4096
object size = 1900
elt_num = 10
With your calculation, you will request (11+2-1)/2 = 6 pages.
But actually you may need 10 pages (max), since the number of object per
page matching the alignement constraint is 1, not 2.
