Commit d76cd984 authored by Jim Harris's avatar Jim Harris Committed by Daniel Verkamp
Browse files

nvme: optimize nvme_allocate_request memsets 



The memset was zeroing a lot of bytes that get
initialized either later in this function or elsewhere
in the submission code path.  Eliminating these
extra memsets saves a few nanoseconds of CPU overhead
in the NVMe submission path.

Note: one use of the cpl data member depended on
the nvme_allocate_request memset.  Since this use
case is not in the primary I/O path, just memset it
in that specific location before using it.

Signed-off-by: default avatarJim Harris <james.r.harris@intel.com>
Change-Id: Ife483a4d9c24c033cc7d26d94ec1700905a936f4
Reviewed-on: https://review.gerrithub.io/413153


Tested-by: default avatarSPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: default avatarDaniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
parent 7dff719f

lib/nvme/nvme.c

+7 −3
Original line number Diff line number Diff line
@@ -157,14 +157,18 @@ nvme_allocate_request(struct spdk_nvme_qpair *qpair, 
	STAILQ_REMOVE_HEAD(&qpair->free_req, stailq);



	/*

	 * Only memset up to (but not including) the children

	 *  TAILQ_ENTRY.  children, and following members, are

	 * Only memset/zero fields that need it.  All other fields

	 *  will be initialized appropriately either later in this

	 *  function, or before they are needed later in the

	 *  submission patch.  For example, the children

	 *  TAILQ_ENTRY and following members are

	 *  only used as part of I/O splitting so we avoid

	 *  memsetting them until it is actually needed.

	 *  They will be initialized in nvme_request_add_child()

	 *  if the request is split.

	 */

	memset(req, 0, offsetof(struct nvme_request, children));

	memset(req, 0, offsetof(struct nvme_request, payload_size));



	req->cb_fn = cb_fn;

	req->cb_arg = cb_arg;

	req->payload = *payload;

lib/nvme/nvme_ctrlr_cmd.c

+1 −0
Original line number Diff line number Diff line
@@ -465,6 +465,7 @@ spdk_nvme_ctrlr_cmd_abort_cpl(void *ctx, const struct spdk_nvme_cpl *cpl) 
		rc = nvme_ctrlr_submit_admin_request(ctrlr, next);

		if (rc < 0) {

			SPDK_ERRLOG("Failed to submit queued abort.\n");

			memset(&next->cpl, 0, sizeof(next->cpl));

			next->cpl.status.sct = SPDK_NVME_SCT_GENERIC;

			next->cpl.status.sc = SPDK_NVME_SC_INTERNAL_DEVICE_ERROR;

			next->cpl.status.dnr = 1;

lib/nvme/nvme_internal.h

+7 −6
Original line number Diff line number Diff line
@@ -180,11 +180,6 @@ nvme_payload_type(const struct nvme_payload *payload) { 
struct nvme_request {

	struct spdk_nvme_cmd		cmd;



	/**

	 * Data payload for this request's command.

	 */

	struct nvme_payload		payload;



	uint8_t				retries;



	/**
@@ -192,7 +187,6 @@ struct nvme_request { 
	 *  request which was split into multiple child requests.

	 */

	uint16_t			num_children;

	uint32_t			payload_size;



	/**

	 * Offset in bytes from the beginning of payload for this request.
@@ -201,6 +195,13 @@ struct nvme_request { 
	uint32_t			payload_offset;

	uint32_t			md_offset;



	uint32_t			payload_size;



	/**

	 * Data payload for this request's command.

	 */

	struct nvme_payload		payload;



	spdk_nvme_cmd_cb		cb_fn;

	void				*cb_arg;

	STAILQ_ENTRY(nvme_request)	stailq;