custom align for mempool elements

PATCH Gregory Etelson 2 participants 4 messages Apr 26, 2017 – May 10, 2017

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Gregory Etelson

author

2017-04-26 04:00 UTC #0 lore raw

Signed-off-by Gregory Etelson <[email protected]>

---
 lib/librte_mempool/rte_mempool.c | 27 ++++++++++++++++++++-------
 lib/librte_mempool/rte_mempool.h |  1 +
 2 files changed, 21 insertions(+), 7 deletions(-)

lib/librte_mempool/rte_mempool.c +20 -7

index f65310f..c780df3 100644
@@ -382,7 +382,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
 	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;
+		off = RTE_PTR_ALIGN_CEIL(vaddr, mp->elt_align) - vaddr;
 
 	while (off + total_elt_sz <= len && mp->populated_size < mp->size) {
 		off += mp->header_size;

@@ -392,6 +392,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
 		else
 			mempool_add_elem(mp, (char *)vaddr + off, paddr + off);
 		off += mp->elt_size + mp->trailer_size;
+		off = RTE_ALIGN_CEIL(off, mp->elt_align);
 		i++;
 	}

@@ -508,6 +509,20 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
 	return ret;
 }
 
+static uint32_t
+mempool_default_elt_aligment(void)
+{
+	uint32_t align;
+	if (rte_xen_dom0_supported()) {
+		   align = RTE_PGSIZE_2M;;
+	} else if (rte_eal_has_hugepages()) {
+		   align = RTE_CACHE_LINE_SIZE;
+	} else {
+		   align = getpagesize();
+	}
+	return align;
+}
+
 /* Default function to populate the mempool: allocate memory in memzones,
  * and populate them. Return the number of objects added, or a negative
  * value on error.

@@ -518,7 +533,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 	int mz_flags = RTE_MEMZONE_1GB|RTE_MEMZONE_SIZE_HINT_ONLY;
 	char mz_name[RTE_MEMZONE_NAMESIZE];
 	const struct rte_memzone *mz;
-	size_t size, total_elt_sz, align, pg_sz, pg_shift;
+	size_t size, total_elt_sz, pg_sz, pg_shift;
 	phys_addr_t paddr;
 	unsigned mz_id, n;
 	int ret;

@@ -530,15 +545,12 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 	if (rte_xen_dom0_supported()) {
 		pg_sz = RTE_PGSIZE_2M;
 		pg_shift = rte_bsf32(pg_sz);
-		align = pg_sz;
 	} else if (rte_eal_has_hugepages()) {
 		pg_shift = 0; /* not needed, zone is physically contiguous */
 		pg_sz = 0;
-		align = RTE_CACHE_LINE_SIZE;
 	} else {
 		pg_sz = getpagesize();
 		pg_shift = rte_bsf32(pg_sz);
-		align = pg_sz;
 	}
 
 	total_elt_sz = mp->header_size + mp->elt_size + mp->trailer_size;

@@ -553,11 +565,11 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 		}
 
 		mz = rte_memzone_reserve_aligned(mz_name, size,
-			mp->socket_id, mz_flags, align);
+			mp->socket_id, mz_flags, mp->elt_align);
 		/* not enough memory, retry with the biggest zone we have */
 		if (mz == NULL)
 			mz = rte_memzone_reserve_aligned(mz_name, 0,
-				mp->socket_id, mz_flags, align);
+				mp->socket_id, mz_flags, mp->elt_align);
 		if (mz == NULL) {
 			ret = -rte_errno;
 			goto fail;

@@ -827,6 +839,7 @@ rte_mempool_create_empty(const char *name, unsigned n, unsigned elt_size,
 	/* Size of default caches, zero means disabled. */
 	mp->cache_size = cache_size;
 	mp->private_data_size = private_data_size;
+	mp->elt_align = mempool_default_elt_aligment();
 	STAILQ_INIT(&mp->elt_list);
 	STAILQ_INIT(&mp->mem_list);

lib/librte_mempool/rte_mempool.h +1 -0

index 48bc8ea..6631973 100644
@@ -245,6 +245,7 @@ struct rte_mempool {
 	 * this mempool.
 	 */
 	int32_t ops_index;
+	uint32_t elt_align;
 
 	struct rte_mempool_cache *local_cache; /**< Per-lcore local cache */

Signature · 1 line

2.9.3

Olivier Matz

2017-05-05 11:26 UTC #1 lore raw

Hi Gregory,

Quoted 100 lines · Gregory Etelson

Signed-off-by Gregory Etelson <[email protected]>

---
 lib/librte_mempool/rte_mempool.c | 27 ++++++++++++++++++++-------
 lib/librte_mempool/rte_mempool.h |  1 +
 2 files changed, 21 insertions(+), 7 deletions(-)

lib/librte_mempool/rte_mempool.c +20 -7

index f65310f..c780df3 100644
@@ -382,7 +382,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
 	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;
+		off = RTE_PTR_ALIGN_CEIL(vaddr, mp->elt_align) - vaddr;
 
 	while (off + total_elt_sz <= len && mp->populated_size < mp->size) {
 		off += mp->header_size;

@@ -392,6 +392,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
 		else
 			mempool_add_elem(mp, (char *)vaddr + off, paddr + off);
 		off += mp->elt_size + mp->trailer_size;
+		off = RTE_ALIGN_CEIL(off, mp->elt_align);
 		i++;
 	}

@@ -508,6 +509,20 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
 	return ret;
 }
 
+static uint32_t
+mempool_default_elt_aligment(void)
+{
+	uint32_t align;
+	if (rte_xen_dom0_supported()) {
+		   align = RTE_PGSIZE_2M;;
+	} else if (rte_eal_has_hugepages()) {
+		   align = RTE_CACHE_LINE_SIZE;
+	} else {
+		   align = getpagesize();
+	}
+	return align;
+}
+
 /* Default function to populate the mempool: allocate memory in memzones,
  * and populate them. Return the number of objects added, or a negative
  * value on error.

@@ -518,7 +533,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 	int mz_flags = RTE_MEMZONE_1GB|RTE_MEMZONE_SIZE_HINT_ONLY;
 	char mz_name[RTE_MEMZONE_NAMESIZE];
 	const struct rte_memzone *mz;
-	size_t size, total_elt_sz, align, pg_sz, pg_shift;
+	size_t size, total_elt_sz, pg_sz, pg_shift;
 	phys_addr_t paddr;
 	unsigned mz_id, n;
 	int ret;

@@ -530,15 +545,12 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 	if (rte_xen_dom0_supported()) {
 		pg_sz = RTE_PGSIZE_2M;
 		pg_shift = rte_bsf32(pg_sz);
-		align = pg_sz;
 	} else if (rte_eal_has_hugepages()) {
 		pg_shift = 0; /* not needed, zone is physically contiguous */
 		pg_sz = 0;
-		align = RTE_CACHE_LINE_SIZE;
 	} else {
 		pg_sz = getpagesize();
 		pg_shift = rte_bsf32(pg_sz);
-		align = pg_sz;
 	}
 
 	total_elt_sz = mp->header_size + mp->elt_size + mp->trailer_size;

@@ -553,11 +565,11 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 		}
 
 		mz = rte_memzone_reserve_aligned(mz_name, size,
-			mp->socket_id, mz_flags, align);
+			mp->socket_id, mz_flags, mp->elt_align);
 		/* not enough memory, retry with the biggest zone we have */
 		if (mz == NULL)
 			mz = rte_memzone_reserve_aligned(mz_name, 0,
-				mp->socket_id, mz_flags, align);
+				mp->socket_id, mz_flags, mp->elt_align);
 		if (mz == NULL) {
 			ret = -rte_errno;
 			goto fail;

@@ -827,6 +839,7 @@ rte_mempool_create_empty(const char *name, unsigned n, unsigned elt_size,
 	/* Size of default caches, zero means disabled. */
 	mp->cache_size = cache_size;
 	mp->private_data_size = private_data_size;
+	mp->elt_align = mempool_default_elt_aligment();
 	STAILQ_INIT(&mp->elt_list);
 	STAILQ_INIT(&mp->mem_list);

lib/librte_mempool/rte_mempool.h +0 -0

index 48bc8ea..6631973 100644

lib/librte_mempool/rte_mempool.h struct rte_mempool { · line 251

Quoted 7 lines

lib/librte_mempool/rte_mempool.h +1 -0

@@ -245,6 +245,7 @@ struct rte_mempool {
 	 * this mempool.
 	 */
 	int32_t ops_index;
+	uint32_t elt_align;
 
 	struct rte_mempool_cache *local_cache; /**< Per-lcore local cache */

It looks the patch will break the ABI (the mempool structure), so it has to follow the abi deprecation process (= a notice in 17.05 and the patch for 17.08).

Could you give us some details about why you need such feature, how you use it (since no API is added)?

Thanks,
Olivier

Gregory Etelson

author

2017-05-05 17:23 UTC #2 lore raw

Hello Oliver,

Our application writes data from incoming MBUFs to storage device. For performance considerations we use O_DIRECT storage access and work in 'zero copy' data mode.
To achieve the 'zero copy' we MUST arrange data in all MBUFs to be 512 bytes aligned
With pre-calculated custom pool element alignment and right
RTE_PKTMBUF_HEADROOM value
we can set MBUF data alignment to any value. In our case, 512 bytes

Current implementation sets custom mempool alignment like this:

struct rte_mempool *mp = rte_mempool_create_empty("MBUF pool",
mbufs_count,
elt_size, cache_size, sizeof(struct
rte_pktmbuf_pool_private), rte_socket_id(), 0);

    rte_pktmbuf_pool_init(mp, &mbp_priv);
  *mp->elt_align = align*;
    rte_mempool_populate_default(mp);

Regards,
Gregory

Quoted 137 lines · Olivier Matz

Hi Gregory,
lib/librte_mempool/rte_
Quoted 7 lines · Gregory Etelson
Signed-off-by Gregory Etelson <[email protected]>
---
 lib/librte_mempool/rte_mempool.c | 27 ++++++++++++++++++++-------
 lib/librte_mempool/rte_mempool.h |  1 +
 2 files changed, 21 insertions(+), 7 deletions(-)
lib/librte_mempool/rte_ renamed from lib/librte_mempool/rte_mempool.c +0 -0
mempool.c
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp,
Quoted 4 lines
index f65310f..c780df3 100644
lib/librte_mempool/rte_mempool.c +0 -0
@@ -382,7 +382,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp,
char *vaddr,
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
Quoted 4 lines
lib/librte_mempool/rte_mempool.c +0 -1
      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;
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
Quoted 3 lines
lib/librte_mempool/rte_mempool.c +1 -0
+             off = RTE_PTR_ALIGN_CEIL(vaddr, mp->elt_align) - vaddr;
 
      while (off + total_elt_sz <= len && mp->populated_size < mp->size)
{
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp,
Quoted 2 lines
lib/librte_mempool/rte_mempool.c +0 -0
              off += mp->header_size;
@@ -392,6 +392,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp,
char *vaddr,
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp, · line 393
Quoted 2 lines
lib/librte_mempool/rte_mempool.c +0 -0
              else
                      mempool_add_elem(mp, (char *)vaddr + off, paddr +
off);
lib/librte_mempool/rte_mempool.c rte_mempool_populate_virt(struct rte_mempool *mp,
Quoted 6 lines
lib/librte_mempool/rte_mempool.c +1 -0
              off += mp->elt_size + mp->trailer_size;
+             off = RTE_ALIGN_CEIL(off, mp->elt_align);
              i++;
      }
 
@@ -508,6 +509,20 @@ rte_mempool_populate_virt(struct rte_mempool *mp,
char *addr,
Quoted 8 lines
lib/librte_mempool/rte_mempool.c +5 -0
      return ret;
 }
 
+static uint32_t
+mempool_default_elt_aligment(void)
+{
+     uint32_t align;
+     if (rte_xen_dom0_supported()) {
lib/librte_mempool/rte_mempool.c rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
Quoted 10 lines
lib/librte_mempool/rte_mempool.c +9 -0
+                align = RTE_PGSIZE_2M;;
+     } else if (rte_eal_has_hugepages()) {
+                align = RTE_CACHE_LINE_SIZE;
+     } else {
+                align = getpagesize();
+     }
+     return align;
+}
+
 /* Default function to populate the mempool: allocate memory in
memzones,
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool
Quoted 12 lines
lib/librte_mempool/rte_mempool.c +1 -1
  * and populate them. Return the number of objects added, or a negative
  * value on error.
@@ -518,7 +533,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
      int mz_flags = RTE_MEMZONE_1GB|RTE_MEMZONE_SIZE_HINT_ONLY;
      char mz_name[RTE_MEMZONE_NAMESIZE];
      const struct rte_memzone *mz;
-     size_t size, total_elt_sz, align, pg_sz, pg_shift;
+     size_t size, total_elt_sz, pg_sz, pg_shift;
      phys_addr_t paddr;
      unsigned mz_id, n;
      int ret;
@@ -530,15 +545,12 @@ rte_mempool_populate_default(struct rte_mempool
*mp)
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool *mp)
Quoted 6 lines
lib/librte_mempool/rte_mempool.c +0 -1
      if (rte_xen_dom0_supported()) {
              pg_sz = RTE_PGSIZE_2M;
              pg_shift = rte_bsf32(pg_sz);
-             align = pg_sz;
      } else if (rte_eal_has_hugepages()) {
              pg_shift = 0; /* not needed, zone is physically contiguous
*/
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool
Quoted 10 lines
lib/librte_mempool/rte_mempool.c +0 -2
              pg_sz = 0;
-             align = RTE_CACHE_LINE_SIZE;
      } else {
              pg_sz = getpagesize();
              pg_shift = rte_bsf32(pg_sz);
-             align = pg_sz;
      }
 
      total_elt_sz = mp->header_size + mp->elt_size + mp->trailer_size;
@@ -553,11 +565,11 @@ rte_mempool_populate_default(struct rte_mempool
*mp)
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool *mp)
Quoted 6 lines
lib/librte_mempool/rte_mempool.c +1 -1
              }
 
              mz = rte_memzone_reserve_aligned(mz_name, size,
-                     mp->socket_id, mz_flags, align);
+                     mp->socket_id, mz_flags, mp->elt_align);
              /* not enough memory, retry with the biggest zone we have
*/
lib/librte_mempool/rte_mempool.c rte_mempool_create_empty(const char *name, unsigned
Quoted 8 lines
lib/librte_mempool/rte_mempool.c +1 -1
              if (mz == NULL)
                      mz = rte_memzone_reserve_aligned(mz_name, 0,
-                             mp->socket_id, mz_flags, align);
+                             mp->socket_id, mz_flags, mp->elt_align);
              if (mz == NULL) {
                      ret = -rte_errno;
                      goto fail;
@@ -827,6 +839,7 @@ rte_mempool_create_empty(const char *name, unsigned
n, unsigned elt_size,
lib/librte_mempool/rte_
Quoted 8 lines
lib/librte_mempool/rte_mempool.c +1 -0
      /* Size of default caches, zero means disabled. */
      mp->cache_size = cache_size;
      mp->private_data_size = private_data_size;
+     mp->elt_align = mempool_default_elt_aligment();
      STAILQ_INIT(&mp->elt_list);
      STAILQ_INIT(&mp->mem_list);
 
lib/librte_mempool/rte_ renamed from lib/librte_mempool/rte_mempool.h +0 -0
mempool.h
lib/librte_mempool/rte_mempool.h struct rte_mempool { · line 250
Quoted 10 lines
index 48bc8ea..6631973 100644
lib/librte_mempool/rte_mempool.h +1 -0
@@ -245,6 +245,7 @@ struct rte_mempool {
       * this mempool.
       */
      int32_t ops_index;
+     uint32_t elt_align;
 
      struct rte_mempool_cache *local_cache; /**< Per-lcore local cache
*/
Quoted 1 line
It looks the patch will break the ABI (the mempool structure), so it has to follow the abi deprecation process (= a notice in 17.05 and the patch for 17.08).
Could you give us some details about why you need such feature, how you use it (since no API is added)?
Thanks,
Olivier

Olivier Matz

2017-05-10 15:01 UTC #3 lore raw

Hi Gregory,

Quoted 13 lines · Gregory Etelson

Hello Oliver,
Our application writes data from incoming MBUFs to storage device. For performance considerations we use O_DIRECT storage access and work in 'zero copy' data mode.
To achieve the 'zero copy' we MUST arrange data in all MBUFs to be 512 bytes aligned
With pre-calculated custom pool element alignment and right
RTE_PKTMBUF_HEADROOM value
we can set MBUF data alignment to any value. In our case, 512 bytes
Current implementation sets custom mempool alignment like this:

Quoted 8 lines

struct rte_mempool *mp = rte_mempool_create_empty("MBUF pool",
mbufs_count,
elt_size, cache_size, sizeof(struct
rte_pktmbuf_pool_private), rte_socket_id(), 0);
    rte_pktmbuf_pool_init(mp, &mbp_priv);
  *mp->elt_align = align*;
    rte_mempool_populate_default(mp);

I think we should try to avoid modifying mp->elt_align directly. A new api could be added for that, maybe something like:

int rte_mempool_set_obj_align(struct rte_mempool *mp, size_t align) size_t rte_mempool_get_obj_align(struct rte_mempool *mp)

The set() function would have to be called before mempool_populate().

We need to take care about conflict with the MEMPOOL_F_NO_CACHE_ALIGN flag. I think we should keep the compat for this flag user. This flag could be deprecated and removed later. I think there may also be some conflicts with MEMPOOL_F_NO_SPREAD.

As I said in my previous mail, if the patch breaks the ABI (the mempool structure), it has to follow the abi deprecation process (= a notice in 17.05 and the patch for 17.08).

I'm afraid it would be quite late for the notice though.

Regards,
Olivier

Quoted 143 lines

Regards,
Gregory
Quoted 137 lines · Olivier Matz
Hi Gregory,
lib/librte_mempool/rte_
Quoted 7 lines · Gregory Etelson
Signed-off-by Gregory Etelson <[email protected]>
---
 lib/librte_mempool/rte_mempool.c | 27 ++++++++++++++++++++-------
 lib/librte_mempool/rte_mempool.h |  1 +
 2 files changed, 21 insertions(+), 7 deletions(-)
lib/librte_mempool/rte_ renamed from lib/librte_mempool/rte_mempool.c +0 -0
mempool.c
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp,
Quoted 4 lines
index f65310f..c780df3 100644
lib/librte_mempool/rte_mempool.c +0 -0
@@ -382,7 +382,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp,  
char *vaddr,
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
Quoted 4 lines
lib/librte_mempool/rte_mempool.c +0 -1
      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;
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
Quoted 3 lines
lib/librte_mempool/rte_mempool.c +1 -0
+             off = RTE_PTR_ALIGN_CEIL(vaddr, mp->elt_align) - vaddr;
 
      while (off + total_elt_sz <= len && mp->populated_size < mp->size)  
{
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp,
Quoted 2 lines
lib/librte_mempool/rte_mempool.c +0 -0
              off += mp->header_size;
@@ -392,6 +392,7 @@ rte_mempool_populate_phys(struct rte_mempool *mp,  
char *vaddr,
lib/librte_mempool/rte_mempool.c rte_mempool_populate_phys(struct rte_mempool *mp, · line 393
Quoted 2 lines
lib/librte_mempool/rte_mempool.c +0 -0
              else
                      mempool_add_elem(mp, (char *)vaddr + off, paddr +  
off);
lib/librte_mempool/rte_mempool.c rte_mempool_populate_virt(struct rte_mempool *mp,
Quoted 6 lines
lib/librte_mempool/rte_mempool.c +1 -0
              off += mp->elt_size + mp->trailer_size;
+             off = RTE_ALIGN_CEIL(off, mp->elt_align);
              i++;
      }
 
@@ -508,6 +509,20 @@ rte_mempool_populate_virt(struct rte_mempool *mp,  
char *addr,
Quoted 8 lines
lib/librte_mempool/rte_mempool.c +5 -0
      return ret;
 }
 
+static uint32_t
+mempool_default_elt_aligment(void)
+{
+     uint32_t align;
+     if (rte_xen_dom0_supported()) {
lib/librte_mempool/rte_mempool.c rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
Quoted 10 lines
lib/librte_mempool/rte_mempool.c +9 -0
+                align = RTE_PGSIZE_2M;;
+     } else if (rte_eal_has_hugepages()) {
+                align = RTE_CACHE_LINE_SIZE;
+     } else {
+                align = getpagesize();
+     }
+     return align;
+}
+
 /* Default function to populate the mempool: allocate memory in  
memzones,
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool
Quoted 12 lines
lib/librte_mempool/rte_mempool.c +1 -1
  * and populate them. Return the number of objects added, or a negative
  * value on error.
@@ -518,7 +533,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
      int mz_flags = RTE_MEMZONE_1GB|RTE_MEMZONE_SIZE_HINT_ONLY;
      char mz_name[RTE_MEMZONE_NAMESIZE];
      const struct rte_memzone *mz;
-     size_t size, total_elt_sz, align, pg_sz, pg_shift;
+     size_t size, total_elt_sz, pg_sz, pg_shift;
      phys_addr_t paddr;
      unsigned mz_id, n;
      int ret;
@@ -530,15 +545,12 @@ rte_mempool_populate_default(struct rte_mempool  
*mp)
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool *mp)
Quoted 6 lines
lib/librte_mempool/rte_mempool.c +0 -1
      if (rte_xen_dom0_supported()) {
              pg_sz = RTE_PGSIZE_2M;
              pg_shift = rte_bsf32(pg_sz);
-             align = pg_sz;
      } else if (rte_eal_has_hugepages()) {
              pg_shift = 0; /* not needed, zone is physically contiguous  
*/
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool
Quoted 10 lines
lib/librte_mempool/rte_mempool.c +0 -2
              pg_sz = 0;
-             align = RTE_CACHE_LINE_SIZE;
      } else {
              pg_sz = getpagesize();
              pg_shift = rte_bsf32(pg_sz);
-             align = pg_sz;
      }
 
      total_elt_sz = mp->header_size + mp->elt_size + mp->trailer_size;
@@ -553,11 +565,11 @@ rte_mempool_populate_default(struct rte_mempool  
*mp)
lib/librte_mempool/rte_mempool.c rte_mempool_populate_default(struct rte_mempool *mp)
Quoted 6 lines
lib/librte_mempool/rte_mempool.c +1 -1
              }
 
              mz = rte_memzone_reserve_aligned(mz_name, size,
-                     mp->socket_id, mz_flags, align);
+                     mp->socket_id, mz_flags, mp->elt_align);
              /* not enough memory, retry with the biggest zone we have  
*/
lib/librte_mempool/rte_mempool.c rte_mempool_create_empty(const char *name, unsigned
Quoted 8 lines
lib/librte_mempool/rte_mempool.c +1 -1
              if (mz == NULL)
                      mz = rte_memzone_reserve_aligned(mz_name, 0,
-                             mp->socket_id, mz_flags, align);
+                             mp->socket_id, mz_flags, mp->elt_align);
              if (mz == NULL) {
                      ret = -rte_errno;
                      goto fail;
@@ -827,6 +839,7 @@ rte_mempool_create_empty(const char *name, unsigned  
n, unsigned elt_size,
lib/librte_mempool/rte_
Quoted 8 lines
lib/librte_mempool/rte_mempool.c +1 -0
      /* Size of default caches, zero means disabled. */
      mp->cache_size = cache_size;
      mp->private_data_size = private_data_size;
+     mp->elt_align = mempool_default_elt_aligment();
      STAILQ_INIT(&mp->elt_list);
      STAILQ_INIT(&mp->mem_list);
 
lib/librte_mempool/rte_ renamed from lib/librte_mempool/rte_mempool.h +0 -0
mempool.h
lib/librte_mempool/rte_mempool.h struct rte_mempool { · line 250
Quoted 10 lines
index 48bc8ea..6631973 100644
lib/librte_mempool/rte_mempool.h +1 -0
@@ -245,6 +245,7 @@ struct rte_mempool {
       * this mempool.
       */
      int32_t ops_index;
+     uint32_t elt_align;
 
      struct rte_mempool_cache *local_cache; /**< Per-lcore local cache  
*/
Quoted 1 line
It looks the patch will break the ABI (the mempool structure), so it has to follow the abi deprecation process (= a notice in 17.05 and the patch for 17.08).
Could you give us some details about why you need such feature, how you use it (since no API is added)?
Thanks,
Olivier