Commit d3cf5611 authored by Tomasz Zawadzki's avatar Tomasz Zawadzki
Browse files

nvme/pcie: reduce physically contiguous memory for CQ/SQ 



Following patch made sure that CQ/SQ are allocated in
physically contiguous manner:
(64db67) nvme/pcie: make sure sq and cq are physically contiguous

Using MAX_IO_QUEUE_ENTRIES is enough to make sure that either
queue does not span multiple hugepages.

Yet the patch made sure that whole page is occupied only
by the queue. Which unnecessarily increases memory consumption
up to two hugepages per each qpair.

This patch changes it so that each queue alignment is limited
up to its size.

Changes in hugepages consumed when allocating io_qpair in hello_world
application:
io_queue_size		Without patch	With patch
256			8MiB		0MiB
1024			12MiB		4MiB
4096			24MiB		16MiB
Note: 0MiB means no new hugepages were required and qpair fits into
previously allocated hugepages (see all steps before io_qpair
allocation in hello_world).

Intersting result of this patch is that since we required alignment
up to the hugepage size this resulted in reserving even two 2MiB
hugepages to account for DPDK internal malloc trailing element.
See alloc_sz in try_expand_heap_primary() within malloc_heap.c

This patch not only reduces overall memory reserved for the
queues, but decreases increase in heap consumption on DPDK side.

Signed-off-by: default avatarTomasz Zawadzki <tomasz.zawadzki@intel.com>
Change-Id: I75bf86e93674b4822d8204df3fb99458dec61e9c
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/2244


Community-CI: Mellanox Build Bot
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
parent 2623c4c4

lib/nvme/nvme_pcie.c

+9 −8
Original line number Diff line number Diff line
@@ -1032,7 +1032,8 @@ nvme_pcie_qpair_construct(struct spdk_nvme_qpair *qpair, 
	uint16_t		i;

	volatile uint32_t	*doorbell_base;

	uint16_t		num_trackers;

	size_t			page_align = VALUE_2MB;

	size_t			page_align = sysconf(_SC_PAGESIZE);

	size_t			queue_align, queue_len;

	uint32_t                flags = SPDK_MALLOC_DMA;

	uint64_t		sq_paddr = 0;

	uint64_t		cq_paddr = 0;
@@ -1070,7 +1071,7 @@ nvme_pcie_qpair_construct(struct spdk_nvme_qpair *qpair, 
	/* cmd and cpl rings must be aligned on page size boundaries. */

	if (ctrlr->opts.use_cmb_sqs) {

		pqpair->cmd = nvme_pcie_ctrlr_alloc_cmb(ctrlr, pqpair->num_entries * sizeof(struct spdk_nvme_cmd),

							sysconf(_SC_PAGESIZE), &pqpair->cmd_bus_addr);

							page_align, &pqpair->cmd_bus_addr);

		if (pqpair->cmd != NULL) {

			pqpair->sq_in_cmb = true;

		}
@@ -1083,9 +1084,9 @@ nvme_pcie_qpair_construct(struct spdk_nvme_qpair *qpair, 
			/* To ensure physical address contiguity we make each ring occupy

			 * a single hugepage only. See MAX_IO_QUEUE_ENTRIES.

			 */

			pqpair->cmd = spdk_zmalloc(pqpair->num_entries * sizeof(struct spdk_nvme_cmd),

						   page_align, NULL,

						   SPDK_ENV_SOCKET_ID_ANY, flags);

			queue_len = pqpair->num_entries * sizeof(struct spdk_nvme_cmd);

			queue_align = spdk_max(spdk_align32pow2(queue_len), page_align);

			pqpair->cmd = spdk_zmalloc(queue_len, queue_align, NULL, SPDK_ENV_SOCKET_ID_ANY, flags);

			if (pqpair->cmd == NULL) {

				SPDK_ERRLOG("alloc qpair_cmd failed\n");

				return -ENOMEM;
@@ -1106,9 +1107,9 @@ nvme_pcie_qpair_construct(struct spdk_nvme_qpair *qpair, 
	if (pqpair->cq_vaddr) {

		pqpair->cpl = pqpair->cq_vaddr;

	} else {

		pqpair->cpl = spdk_zmalloc(pqpair->num_entries * sizeof(struct spdk_nvme_cpl),

					   page_align, NULL,

					   SPDK_ENV_SOCKET_ID_ANY, flags);

		queue_len = pqpair->num_entries * sizeof(struct spdk_nvme_cpl);

		queue_align = spdk_max(spdk_align32pow2(queue_len), page_align);

		pqpair->cpl = spdk_zmalloc(queue_len, queue_align, NULL, SPDK_ENV_SOCKET_ID_ANY, flags);

		if (pqpair->cpl == NULL) {

			SPDK_ERRLOG("alloc qpair_cpl failed\n");

			return -ENOMEM;