[dpdk-dev] [PATCH v8 2/4] mempool: add non-IO flag

[Dmitry Kozlyuk <dkozlyuk@oss.nvidia.com>]

Mempool is a generic allocator that is not necessarily used
for device IO operations and its memory for DMA.
Add MEMPOOL_F_NON_IO flag to mark such mempools automatically
a) if their objects are not contiguous;
b) if IOVA is not available for any object.
Other components can inspect this flag
in order to optimize their memory management.

Discussion: https://mails.dpdk.org/archives/dev/2021-August/216654.html

Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
---
 app/proc-info/main.c                   |   6 +-
 app/test/test_mempool.c                | 114 +++++++++++++++++++++++++
 doc/guides/rel_notes/release_21_11.rst |   3 +
 lib/mempool/rte_mempool.c              |  10 +++
 lib/mempool/rte_mempool.h              |   2 +
 5 files changed, 133 insertions(+), 2 deletions(-)

diff --git a/app/proc-info/main.c b/app/proc-info/main.c
index a8e928fa9f..8ec9cadd79 100644
--- a/app/proc-info/main.c
+++ b/app/proc-info/main.c
@@ -1295,7 +1295,8 @@ show_mempool(char *name)
 				"\t  -- No cache align (%c)\n"
 				"\t  -- SP put (%c), SC get (%c)\n"
 				"\t  -- Pool created (%c)\n"
-				"\t  -- No IOVA config (%c)\n",
+				"\t  -- No IOVA config (%c)\n"
+				"\t  -- Not used for IO (%c)\n",
 				ptr->name,
 				ptr->socket_id,
 				(flags & MEMPOOL_F_NO_SPREAD) ? 'y' : 'n',
@@ -1303,7 +1304,8 @@ show_mempool(char *name)
 				(flags & MEMPOOL_F_SP_PUT) ? 'y' : 'n',
 				(flags & MEMPOOL_F_SC_GET) ? 'y' : 'n',
 				(flags & MEMPOOL_F_POOL_CREATED) ? 'y' : 'n',
-				(flags & MEMPOOL_F_NO_IOVA_CONTIG) ? 'y' : 'n');
+				(flags & MEMPOOL_F_NO_IOVA_CONTIG) ? 'y' : 'n',
+				(flags & MEMPOOL_F_NON_IO) ? 'y' : 'n');
 			printf("  - Size %u Cache %u element %u\n"
 				"  - header %u trailer %u\n"
 				"  - private data size %u\n",
diff --git a/app/test/test_mempool.c b/app/test/test_mempool.c
index c39c83256e..81800b7122 100644
--- a/app/test/test_mempool.c
+++ b/app/test/test_mempool.c
@@ -12,6 +12,7 @@
 #include <sys/queue.h>
 
 #include <rte_common.h>
+#include <rte_eal_paging.h>
 #include <rte_log.h>
 #include <rte_debug.h>
 #include <rte_errno.h>
@@ -729,6 +730,111 @@ test_mempool_events_safety(void)
 #pragma pop_macro("RTE_TEST_TRACE_FAILURE")
 }
 
+#pragma push_macro("RTE_TEST_TRACE_FAILURE")
+#undef RTE_TEST_TRACE_FAILURE
+#define RTE_TEST_TRACE_FAILURE(...) do { \
+		ret = TEST_FAILED; \
+		goto exit; \
+	} while (0)
+
+static int
+test_mempool_flag_non_io_set_when_no_iova_contig_set(void)
+{
+	struct rte_mempool *mp = NULL;
+	int ret;
+
+	mp = rte_mempool_create_empty("empty", MEMPOOL_SIZE,
+				      MEMPOOL_ELT_SIZE, 0, 0,
+				      SOCKET_ID_ANY, MEMPOOL_F_NO_IOVA_CONTIG);
+	RTE_TEST_ASSERT_NOT_NULL(mp, "Cannot create mempool: %s",
+				 rte_strerror(rte_errno));
+	rte_mempool_set_ops_byname(mp, rte_mbuf_best_mempool_ops(), NULL);
+	ret = rte_mempool_populate_default(mp);
+	RTE_TEST_ASSERT(ret > 0, "Failed to populate mempool: %s",
+			rte_strerror(rte_errno));
+	RTE_TEST_ASSERT(mp->flags & MEMPOOL_F_NON_IO,
+			"NON_IO flag is not set when NO_IOVA_CONTIG is set");
+	ret = TEST_SUCCESS;
+exit:
+	rte_mempool_free(mp);
+	return ret;
+}
+
+static int
+test_mempool_flag_non_io_unset_when_populated_with_valid_iova(void)
+{
+	void *virt = NULL;
+	rte_iova_t iova;
+	size_t page_size = RTE_PGSIZE_2M;
+	struct rte_mempool *mp = NULL;
+	int ret;
+
+	/*
+	 * Since objects from the pool are never used in the test,
+	 * we don't care for contiguous IOVA, on the other hand,
+	 * reiuring it could cause spurious test failures.
+	 */
+	virt = rte_malloc("test_mempool", 3 * page_size, page_size);
+	RTE_TEST_ASSERT_NOT_NULL(virt, "Cannot allocate memory");
+	iova = rte_mem_virt2iova(virt);
+	RTE_TEST_ASSERT_NOT_EQUAL(iova,  RTE_BAD_IOVA, "Cannot get IOVA");
+	mp = rte_mempool_create_empty("empty", MEMPOOL_SIZE,
+				      MEMPOOL_ELT_SIZE, 0, 0,
+				      SOCKET_ID_ANY, 0);
+	RTE_TEST_ASSERT_NOT_NULL(mp, "Cannot create mempool: %s",
+				 rte_strerror(rte_errno));
+
+	ret = rte_mempool_populate_iova(mp, RTE_PTR_ADD(virt, 1 * page_size),
+					RTE_BAD_IOVA, page_size, NULL, NULL);
+	RTE_TEST_ASSERT(ret > 0, "Failed to populate mempool: %s",
+			rte_strerror(rte_errno));
+	RTE_TEST_ASSERT(mp->flags & MEMPOOL_F_NON_IO,
+			"NON_IO flag is not set when mempool is populated with only RTE_BAD_IOVA");
+
+	ret = rte_mempool_populate_iova(mp, virt, iova, page_size, NULL, NULL);
+	RTE_TEST_ASSERT(ret > 0, "Failed to populate mempool: %s",
+			rte_strerror(rte_errno));
+	RTE_TEST_ASSERT(!(mp->flags & MEMPOOL_F_NON_IO),
+			"NON_IO flag is not unset when mempool is populated with valid IOVA");
+
+	ret = rte_mempool_populate_iova(mp, RTE_PTR_ADD(virt, 2 * page_size),
+					RTE_BAD_IOVA, page_size, NULL, NULL);
+	RTE_TEST_ASSERT(ret > 0, "Failed to populate mempool: %s",
+			rte_strerror(rte_errno));
+	RTE_TEST_ASSERT(!(mp->flags & MEMPOOL_F_NON_IO),
+			"NON_IO flag is set even when some objects have valid IOVA");
+	ret = TEST_SUCCESS;
+
+exit:
+	rte_mempool_free(mp);
+	rte_free(virt);
+	return ret;
+}
+
+static int
+test_mempool_flag_non_io_unset_by_default(void)
+{
+	struct rte_mempool *mp;
+	int ret;
+
+	mp = rte_mempool_create_empty("empty", MEMPOOL_SIZE,
+				      MEMPOOL_ELT_SIZE, 0, 0,
+				      SOCKET_ID_ANY, 0);
+	RTE_TEST_ASSERT_NOT_NULL(mp, "Cannot create mempool: %s",
+				 rte_strerror(rte_errno));
+	ret = rte_mempool_populate_default(mp);
+	RTE_TEST_ASSERT_EQUAL(ret, (int)mp->size, "Failed to populate mempool: %s",
+			      rte_strerror(rte_errno));
+	RTE_TEST_ASSERT(!(mp->flags & MEMPOOL_F_NON_IO),
+			"NON_IO flag is set by default");
+	ret = TEST_SUCCESS;
+exit:
+	rte_mempool_free(mp);
+	return ret;
+}
+
+#pragma pop_macro("RTE_TEST_TRACE_FAILURE")
+
 static int
 test_mempool(void)
 {
@@ -914,6 +1020,14 @@ test_mempool(void)
 	if (test_mempool_events_safety() < 0)
 		GOTO_ERR(ret, err);
 
+	/* test NON_IO flag inference */
+	if (test_mempool_flag_non_io_unset_by_default() < 0)
+		GOTO_ERR(ret, err);
+	if (test_mempool_flag_non_io_set_when_no_iova_contig_set() < 0)
+		GOTO_ERR(ret, err);
+	if (test_mempool_flag_non_io_unset_when_populated_with_valid_iova() < 0)
+		GOTO_ERR(ret, err);
+
 	rte_mempool_list_dump(stdout);
 
 	ret = 0;
diff --git a/doc/guides/rel_notes/release_21_11.rst b/doc/guides/rel_notes/release_21_11.rst
index d5435a64aa..f6bb5adeff 100644
--- a/doc/guides/rel_notes/release_21_11.rst
+++ b/doc/guides/rel_notes/release_21_11.rst
@@ -237,6 +237,9 @@ API Changes
   the crypto/security operation. This field will be used to communicate
   events such as soft expiry with IPsec in lookaside mode.
 
+* mempool: Added ``MEMPOOL_F_NON_IO`` flag to give a hint to DPDK components
+  that objects from this pool will not be used for device IO (e.g. DMA).
+
 
 ABI Changes
 -----------
diff --git a/lib/mempool/rte_mempool.c b/lib/mempool/rte_mempool.c
index 8810d08ab5..7d7d97d85d 100644
--- a/lib/mempool/rte_mempool.c
+++ b/lib/mempool/rte_mempool.c
@@ -372,6 +372,10 @@ rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 	STAILQ_INSERT_TAIL(&mp->mem_list, memhdr, next);
 	mp->nb_mem_chunks++;
 
+	/* At least some objects in the pool can now be used for IO. */
+	if (iova != RTE_BAD_IOVA)
+		mp->flags &= ~MEMPOOL_F_NON_IO;
+
 	/* Report the mempool as ready only when fully populated. */
 	if (mp->populated_size >= mp->size)
 		mempool_event_callback_invoke(RTE_MEMPOOL_EVENT_READY, mp);
@@ -851,6 +855,12 @@ rte_mempool_create_empty(const char *name, unsigned n, unsigned elt_size,
 		return NULL;
 	}
 
+	/*
+	 * No objects in the pool can be used for IO until it's populated
+	 * with at least some objects with valid IOVA.
+	 */
+	flags |= MEMPOOL_F_NON_IO;
+
 	/* "no cache align" imply "no spread" */
 	if (flags & MEMPOOL_F_NO_CACHE_ALIGN)
 		flags |= MEMPOOL_F_NO_SPREAD;
diff --git a/lib/mempool/rte_mempool.h b/lib/mempool/rte_mempool.h
index 5799d4a705..b2e20c8855 100644
--- a/lib/mempool/rte_mempool.h
+++ b/lib/mempool/rte_mempool.h
@@ -257,6 +257,8 @@ struct rte_mempool {
 #define MEMPOOL_F_SC_GET         0x0008 /**< Default get is "single-consumer".*/
 #define MEMPOOL_F_POOL_CREATED   0x0010 /**< Internal: pool is created. */
 #define MEMPOOL_F_NO_IOVA_CONTIG 0x0020 /**< Don't need IOVA contiguous objs. */
+/** Internal: no object from the pool can be used for device IO (DMA). */
+#define MEMPOOL_F_NON_IO         0x0040
 
 /**
  * @internal When debug is enabled, store some statistics.
-- 
2.25.1