[dpdk-dev] [PATCH v6 24/70] mempool: add support for the new allocation methods

Anatoly Burakov anatoly.burakov at intel.com
Wed Apr 11 14:29:59 CEST 2018


If a user has specified that the zone should have contiguous memory,
use the new _contig allocation API's instead of normal ones.
Otherwise, account for the fact that unless we're in IOVA_AS_VA
mode, we cannot guarantee that the pages would be physically
contiguous, so we calculate the memzone size and alignments as if
we were getting the smallest page size available.

However, for the non-IOVA contiguous case, existing mempool size
calculation function doesn't give us expected results, because it
will return memzone sizes aligned to page size (e.g. a 1MB mempool
may use an entire 1GB page), therefore in cases where we weren't
specifically asked to reserve non-contiguous memory, first try
reserving a memzone as IOVA-contiguous, and if that fails, then
try reserving with page-aligned size/alignment.

Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
Tested-by: Santosh Shukla <santosh.shukla at caviumnetworks.com>
Tested-by: Hemant Agrawal <hemant.agrawal at nxp.com>
Tested-by: Gowrishankar Muthukrishnan <gowrishankar.m at linux.vnet.ibm.com>
---
 lib/librte_mempool/rte_mempool.c | 148 +++++++++++++++++++++++++++++++++------
 1 file changed, 127 insertions(+), 21 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 54f7f4b..4660cc2 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -3,6 +3,7 @@
  * Copyright(c) 2016 6WIND S.A.
  */
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdint.h>
@@ -98,6 +99,27 @@ static unsigned optimize_object_size(unsigned obj_size)
 	return new_obj_size * RTE_MEMPOOL_ALIGN;
 }
 
+static size_t
+get_min_page_size(void)
+{
+	const struct rte_mem_config *mcfg =
+			rte_eal_get_configuration()->mem_config;
+	int i;
+	size_t min_pagesz = SIZE_MAX;
+
+	for (i = 0; i < RTE_MAX_MEMSEG; i++) {
+		const struct rte_memseg *ms = &mcfg->memseg[i];
+
+		if (ms->addr == NULL)
+			continue;
+
+		if (ms->hugepage_sz < min_pagesz)
+			min_pagesz = ms->hugepage_sz;
+	}
+
+	return min_pagesz == SIZE_MAX ? (size_t) getpagesize() : min_pagesz;
+}
+
 static void
 mempool_add_elem(struct rte_mempool *mp, void *obj, rte_iova_t iova)
 {
@@ -367,16 +389,6 @@ rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 	/* update mempool capabilities */
 	mp->flags |= mp_capa_flags;
 
-	/* Detect pool area has sufficient space for elements */
-	if (mp_capa_flags & MEMPOOL_F_CAPA_PHYS_CONTIG) {
-		if (len < total_elt_sz * mp->size) {
-			RTE_LOG(ERR, MEMPOOL,
-				"pool area %" PRIx64 " not enough\n",
-				(uint64_t)len);
-			return -ENOSPC;
-		}
-	}
-
 	memhdr = rte_zmalloc("MEMPOOL_MEMHDR", sizeof(*memhdr), 0);
 	if (memhdr == NULL)
 		return -ENOMEM;
@@ -549,6 +561,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 	unsigned mz_id, n;
 	unsigned int mp_flags;
 	int ret;
+	bool force_contig, no_contig, try_contig, no_pageshift;
 
 	/* mempool must not be populated */
 	if (mp->nb_mem_chunks != 0)
@@ -563,9 +576,68 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 	/* update mempool capabilities */
 	mp->flags |= mp_flags;
 
-	if (rte_eal_has_hugepages()) {
-		pg_shift = 0; /* not needed, zone is physically contiguous */
+	no_contig = mp->flags & MEMPOOL_F_NO_PHYS_CONTIG;
+	force_contig = mp->flags & MEMPOOL_F_CAPA_PHYS_CONTIG;
+
+	/*
+	 * the following section calculates page shift and page size values.
+	 *
+	 * these values impact the result of rte_mempool_xmem_size(), which
+	 * returns the amount of memory that should be allocated to store the
+	 * desired number of objects. when not zero, it allocates more memory
+	 * for the padding between objects, to ensure that an object does not
+	 * cross a page boundary. in other words, page size/shift are to be set
+	 * to zero if mempool elements won't care about page boundaries.
+	 * there are several considerations for page size and page shift here.
+	 *
+	 * if we don't need our mempools to have physically contiguous objects,
+	 * then just set page shift and page size to 0, because the user has
+	 * indicated that there's no need to care about anything.
+	 *
+	 * if we do need contiguous objects, there is also an option to reserve
+	 * the entire mempool memory as one contiguous block of memory, in
+	 * which case the page shift and alignment wouldn't matter as well.
+	 *
+	 * if we require contiguous objects, but not necessarily the entire
+	 * mempool reserved space to be contiguous, then there are two options.
+	 *
+	 * if our IO addresses are virtual, not actual physical (IOVA as VA
+	 * case), then no page shift needed - our memory allocation will give us
+	 * contiguous physical memory as far as the hardware is concerned, so
+	 * act as if we're getting contiguous memory.
+	 *
+	 * if our IO addresses are physical, we may get memory from bigger
+	 * pages, or we might get memory from smaller pages, and how much of it
+	 * we require depends on whether we want bigger or smaller pages.
+	 * However, requesting each and every memory size is too much work, so
+	 * what we'll do instead is walk through the page sizes available, pick
+	 * the smallest one and set up page shift to match that one. We will be
+	 * wasting some space this way, but it's much nicer than looping around
+	 * trying to reserve each and every page size.
+	 *
+	 * However, since size calculation will produce page-aligned sizes, it
+	 * makes sense to first try and see if we can reserve the entire memzone
+	 * in one contiguous chunk as well (otherwise we might end up wasting a
+	 * 1G page on a 10MB memzone). If we fail to get enough contiguous
+	 * memory, then we'll go and reserve space page-by-page.
+	 */
+	no_pageshift = no_contig || force_contig ||
+			rte_eal_iova_mode() == RTE_IOVA_VA;
+	try_contig = !no_contig && !no_pageshift && rte_eal_has_hugepages();
+	if (force_contig)
+		mz_flags |= RTE_MEMZONE_IOVA_CONTIG;
+
+	if (no_pageshift) {
 		pg_sz = 0;
+		pg_shift = 0;
+		align = RTE_CACHE_LINE_SIZE;
+	} else if (try_contig) {
+		pg_sz = get_min_page_size();
+		pg_shift = rte_bsf32(pg_sz);
+		/* we're trying to reserve contiguous memzone first, so try
+		 * align to cache line; if we fail to reserve a contiguous
+		 * memzone, we'll adjust alignment to equal pagesize later.
+		 */
 		align = RTE_CACHE_LINE_SIZE;
 	} else {
 		pg_sz = getpagesize();
@@ -575,8 +647,13 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 
 	total_elt_sz = mp->header_size + mp->elt_size + mp->trailer_size;
 	for (mz_id = 0, n = mp->size; n > 0; mz_id++, n -= ret) {
-		size = rte_mempool_xmem_size(n, total_elt_sz, pg_shift,
-						mp->flags);
+		unsigned int flags;
+		if (try_contig || no_pageshift)
+			size = rte_mempool_xmem_size(n, total_elt_sz, 0,
+				mp->flags);
+		else
+			size = rte_mempool_xmem_size(n, total_elt_sz, pg_shift,
+				mp->flags);
 
 		ret = snprintf(mz_name, sizeof(mz_name),
 			RTE_MEMPOOL_MZ_FORMAT "_%d", mp->name, mz_id);
@@ -585,23 +662,52 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 			goto fail;
 		}
 
-		mz = rte_memzone_reserve_aligned(mz_name, size,
-			mp->socket_id, mz_flags, align);
-		/* not enough memory, retry with the biggest zone we have */
-		if (mz == NULL)
+		flags = mz_flags;
+
+		/* if we're trying to reserve contiguous memory, add appropriate
+		 * memzone flag.
+		 */
+		if (try_contig)
+			flags |= RTE_MEMZONE_IOVA_CONTIG;
+
+		mz = rte_memzone_reserve_aligned(mz_name, size, mp->socket_id,
+				flags, align);
+
+		/* if we were trying to allocate contiguous memory, adjust
+		 * memzone size and page size to fit smaller page sizes, and
+		 * try again.
+		 */
+		if (mz == NULL && try_contig) {
+			try_contig = false;
+			flags &= ~RTE_MEMZONE_IOVA_CONTIG;
+			align = pg_sz;
+			size = rte_mempool_xmem_size(n, total_elt_sz,
+				pg_shift, mp->flags);
+
+			mz = rte_memzone_reserve_aligned(mz_name, size,
+				mp->socket_id, flags, align);
+		}
+		/* don't try reserving with 0 size if we were asked to reserve
+		 * IOVA-contiguous memory.
+		 */
+		if (!force_contig && mz == NULL) {
+			/* not enough memory, retry with the biggest zone we
+			 * have
+			 */
 			mz = rte_memzone_reserve_aligned(mz_name, 0,
-				mp->socket_id, mz_flags, align);
+					mp->socket_id, flags, align);
+		}
 		if (mz == NULL) {
 			ret = -rte_errno;
 			goto fail;
 		}
 
-		if (mp->flags & MEMPOOL_F_NO_PHYS_CONTIG)
+		if (no_contig)
 			iova = RTE_BAD_IOVA;
 		else
 			iova = mz->iova;
 
-		if (rte_eal_has_hugepages())
+		if (no_pageshift || try_contig)
 			ret = rte_mempool_populate_iova(mp, mz->addr,
 				iova, mz->len,
 				rte_mempool_memchunk_mz_free,
-- 
2.7.4


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