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nvme: optimize nvme_allocate_request memsets

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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: Jim Harris <james.r.harris@intel.com>
Change-Id: Ife483a4d9c24c033cc7d26d94ec1700905a936f4
Reviewed-on: https://review.gerrithub.io/413153
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
This commit is contained in:
Jim Harris 2018-05-31 07:17:27 -07:00 committed by Daniel Verkamp
parent 7dff719f7e
commit d76cd984aa
3 changed files with 15 additions and 9 deletions
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10
lib/nvme/nvme.c
View File

@ -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;

1
lib/nvme/nvme_ctrlr_cmd.c
View File

@ -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;

13
lib/nvme/nvme_internal.h
View File

@ -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;