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nvme: Minimize memory accesses when checking if mmio required

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Don't touch the shadow doorbells if it isn't necessary.

The flag could be combined into a bit mask with other
flags in a future patch.

Change-Id: I9ffd16468d29f0f0868cf849f7fece327eb6a294
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/447967
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
This commit is contained in:
Ben Walker 2019-03-13 15:32:55 -07:00
parent 2c8ffe9e74
commit 581e24004c
1 changed files with 45 additions and 25 deletions
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70
lib/nvme/nvme_pcie.c
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@ -144,18 +144,6 @@ struct nvme_pcie_qpair {
/* Completion queue head doorbell */
volatile uint32_t *cq_hdbl;
/* Submission queue shadow tail doorbell */
volatile uint32_t *sq_shadow_tdbl;
/* Completion queue shadow head doorbell */
volatile uint32_t *cq_shadow_hdbl;
/* Submission queue event index */
volatile uint32_t *sq_eventidx;
/* Completion queue event index */
volatile uint32_t *cq_eventidx;
/* Submission queue */
struct spdk_nvme_cmd *cmd;
@ -178,10 +166,9 @@ struct nvme_pcie_qpair {
uint16_t sq_head;
uint8_t phase;
bool is_enabled;
bool delay_pcie_doorbell;
bool has_shadow_doorbell;
/*
* Base qpair structure.
@ -190,6 +177,20 @@ struct nvme_pcie_qpair {
*/
struct spdk_nvme_qpair qpair;
struct {
/* Submission queue shadow tail doorbell */
volatile uint32_t *sq_tdbl;
/* Completion queue shadow head doorbell */
volatile uint32_t *cq_hdbl;
/* Submission queue event index */
volatile uint32_t *sq_eventidx;
/* Completion queue event index */
volatile uint32_t *cq_eventidx;
} shadow_doorbell;
/*
* Fields below this point should not be touched on the normal I/O path.
*/
@ -1175,11 +1176,16 @@ nvme_pcie_qpair_ring_sq_doorbell(struct spdk_nvme_qpair *qpair)
{
struct nvme_pcie_qpair *pqpair = nvme_pcie_qpair(qpair);
struct nvme_pcie_ctrlr *pctrlr = nvme_pcie_ctrlr(qpair->ctrlr);
bool need_mmio = true;
if (spdk_likely(nvme_pcie_qpair_update_mmio_required(qpair,
pqpair->sq_tail,
pqpair->sq_shadow_tdbl,
pqpair->sq_eventidx))) {
if (spdk_unlikely(pqpair->has_shadow_doorbell)) {
need_mmio = nvme_pcie_qpair_update_mmio_required(qpair,
pqpair->sq_tail,
pqpair->shadow_doorbell.sq_tdbl,
pqpair->shadow_doorbell.sq_eventidx);
}
if (spdk_likely(need_mmio)) {
spdk_wmb();
g_thread_mmio_ctrlr = pctrlr;
spdk_mmio_write_4(pqpair->sq_tdbl, pqpair->sq_tail);
@ -1568,10 +1574,17 @@ _nvme_pcie_ctrlr_create_io_qpair(struct spdk_nvme_ctrlr *ctrlr, struct spdk_nvme
}
if (ctrlr->shadow_doorbell) {
pqpair->sq_shadow_tdbl = ctrlr->shadow_doorbell + (2 * qpair->id + 0) * pctrlr->doorbell_stride_u32;
pqpair->cq_shadow_hdbl = ctrlr->shadow_doorbell + (2 * qpair->id + 1) * pctrlr->doorbell_stride_u32;
pqpair->sq_eventidx = ctrlr->eventidx + (2 * qpair->id + 0) * pctrlr->doorbell_stride_u32;
pqpair->cq_eventidx = ctrlr->eventidx + (2 * qpair->id + 1) * pctrlr->doorbell_stride_u32;
pqpair->shadow_doorbell.sq_tdbl = ctrlr->shadow_doorbell + (2 * qpair->id + 0) *
pctrlr->doorbell_stride_u32;
pqpair->shadow_doorbell.cq_hdbl = ctrlr->shadow_doorbell + (2 * qpair->id + 1) *
pctrlr->doorbell_stride_u32;
pqpair->shadow_doorbell.sq_eventidx = ctrlr->eventidx + (2 * qpair->id + 0) *
pctrlr->doorbell_stride_u32;
pqpair->shadow_doorbell.cq_eventidx = ctrlr->eventidx + (2 * qpair->id + 1) *
pctrlr->doorbell_stride_u32;
pqpair->has_shadow_doorbell = true;
} else {
pqpair->has_shadow_doorbell = false;
}
nvme_pcie_qpair_reset(qpair);
@ -2123,9 +2136,16 @@ nvme_pcie_qpair_process_completions(struct spdk_nvme_qpair *qpair, uint32_t max_
}
if (num_completions > 0) {
if (spdk_likely(nvme_pcie_qpair_update_mmio_required(qpair, pqpair->cq_head,
pqpair->cq_shadow_hdbl,
pqpair->cq_eventidx))) {
bool need_mmio = true;
if (spdk_unlikely(pqpair->has_shadow_doorbell)) {
need_mmio = nvme_pcie_qpair_update_mmio_required(qpair,
pqpair->cq_head,
pqpair->shadow_doorbell.cq_hdbl,
pqpair->shadow_doorbell.cq_eventidx);
}
if (spdk_likely(need_mmio)) {
g_thread_mmio_ctrlr = pctrlr;
spdk_mmio_write_4(pqpair->cq_hdbl, pqpair->cq_head);
g_thread_mmio_ctrlr = NULL;