[dpdk-dev] [PATCH v7 7/8] mempool: introduce block size align flag

[Santosh Shukla]

Some mempool hw like octeontx/fpa block, demands block size
(/total_elem_sz) aligned object start address.

Introducing an MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS flag.
If this flag is set:
- Align object start address(vaddr) to a multiple of total_elt_sz.
- 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 MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS flag is set.

Signed-off-by: Santosh Shukla <santosh.shukla at caviumnetworks.com>
Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
Tested-by: Hemant Agrawal <hemant.agrawal at nxp.com>
---
v6 --> v7:
- Added mask var (a flag checker) in xmem_size/usage() (suggested by Olivier)

Refer [1].
[1] http://dpdk.org/dev/patchwork/patch/28467/

v5 --> v6:
- Renamed from MEMPOOL_F_BLK_ALIGNED_OBJECTS to
MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS. (Suggested by Olivier)
- Updated Capability flag descrioption (Suggested by Olivier) 

History refer [2]
[2] http://dpdk.org/dev/patchwork/patch/28418/

v4 --> v5:
- Added vaddr in git description of patch (suggested by Olivier)
- Renamed to aligned flag to MEMPOOL_F_BLK_ALIGNED_OBJECTS (suggested by
    Olivier)
Refer [3].
[3] http://dpdk.org/dev/patchwork/patch/27600/

 lib/librte_mempool/rte_mempool.c | 21 ++++++++++++++++++---
 lib/librte_mempool/rte_mempool.h | 12 ++++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 146e38675..df9d67ae6 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -239,9 +239,15 @@ 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 unsigned int flags)
+		      unsigned int flags)
 {
 	size_t obj_per_page, pg_num, pg_sz;
+	unsigned int mask;
+
+	mask = MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS | MEMPOOL_F_CAPA_PHYS_CONTIG;
+	if ((flags & mask) == mask)
+		/* alignment need one additional object */
+		elt_num += 1;
 
 	if (total_elt_sz == 0)
 		return 0;
@@ -265,12 +271,18 @@ rte_mempool_xmem_size(uint32_t elt_num, size_t total_elt_sz, uint32_t pg_shift,
 ssize_t
 rte_mempool_xmem_usage(__rte_unused void *vaddr, uint32_t elt_num,
 	size_t total_elt_sz, const phys_addr_t paddr[], uint32_t pg_num,
-	uint32_t pg_shift, __rte_unused unsigned int flags)
+	uint32_t pg_shift, unsigned int flags)
 {
 	uint32_t elt_cnt = 0;
 	phys_addr_t start, end;
 	uint32_t paddr_idx;
 	size_t pg_sz = (size_t)1 << pg_shift;
+	unsigned int mask;
+
+	mask = MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS | MEMPOOL_F_CAPA_PHYS_CONTIG;
+	if ((flags & mask) == mask)
+		/* alignment need one additional object */
+		elt_num += 1;
 
 	/* if paddr is NULL, assume contiguous memory */
 	if (paddr == NULL) {
@@ -390,7 +402,10 @@ rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
 	memhdr->free_cb = free_cb;
 	memhdr->opaque = opaque;
 
-	if (mp->flags & MEMPOOL_F_NO_CACHE_ALIGN)
+	if (mp->flags & MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS)
+		/* align object start address to a multiple of total_elt_sz */
+		off = total_elt_sz - ((uintptr_t)vaddr % total_elt_sz);
+	else if (mp->flags & MEMPOOL_F_NO_CACHE_ALIGN)
 		off = RTE_PTR_ALIGN_CEIL(vaddr, 8) - vaddr;
 	else
 		off = RTE_PTR_ALIGN_CEIL(vaddr, RTE_CACHE_LINE_SIZE) - vaddr;
diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index 734392556..24195dda0 100644
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h
@@ -271,6 +271,18 @@ struct rte_mempool {
  * Note: This flag should not be passed by application.
  */
 #define MEMPOOL_F_CAPA_PHYS_CONTIG 0x0040
+/**
+ * This capability flag is advertised by a mempool handler. Used for a case
+ * where mempool driver wants object start address(vaddr) aligned to block
+ * size(/ total element size).
+ *
+ * Note:
+ * - This flag should not be passed by application.
+ *   Flag used for mempool driver only.
+ * - Mempool driver must also set MEMPOOL_F_CAPA_PHYS_CONTIG flag along with
+ *   MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS.
+ */
+#define MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS 0x0080
 
 /**
  * @internal When debug is enabled, store some statistics.
-- 
2.14.1