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IB/srp: Split send and recieve CQs to reduce number of interrupts
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We can reduce the number of IB interrupts from two interrupts per
srp_queuecommand() call to one by using separate CQs for send and
receive completions and processing send completions by polling every
time a TX IU is allocated.

Receive completion events still trigger an interrupt.

Signed-off-by: Bart Van Assche <bart.vanassche@gmail.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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Bart Van Assche authored and Roland Dreier committed Mar 2, 2010
1 parent 676ad58 commit 9c03dc9
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Showing 2 changed files with 53 additions and 25 deletions.
72 changes: 51 additions & 21 deletions drivers/infiniband/ulp/srp/ib_srp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,8 @@ MODULE_PARM_DESC(mellanox_workarounds,

static void srp_add_one(struct ib_device *device);
static void srp_remove_one(struct ib_device *device);
static void srp_completion(struct ib_cq *cq, void *target_ptr);
static void srp_recv_completion(struct ib_cq *cq, void *target_ptr);
static void srp_send_completion(struct ib_cq *cq, void *target_ptr);
static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event);

static struct scsi_transport_template *ib_srp_transport_template;
Expand Down Expand Up @@ -227,14 +228,22 @@ static int srp_create_target_ib(struct srp_target_port *target)
if (!init_attr)
return -ENOMEM;

target->cq = ib_create_cq(target->srp_host->srp_dev->dev,
srp_completion, NULL, target, SRP_CQ_SIZE, 0);
if (IS_ERR(target->cq)) {
ret = PTR_ERR(target->cq);
target->recv_cq = ib_create_cq(target->srp_host->srp_dev->dev,
srp_recv_completion, NULL, target, SRP_RQ_SIZE, 0);
if (IS_ERR(target->recv_cq)) {
ret = PTR_ERR(target->recv_cq);
goto out;
}

ib_req_notify_cq(target->cq, IB_CQ_NEXT_COMP);
target->send_cq = ib_create_cq(target->srp_host->srp_dev->dev,
srp_send_completion, NULL, target, SRP_SQ_SIZE, 0);
if (IS_ERR(target->send_cq)) {
ret = PTR_ERR(target->send_cq);
ib_destroy_cq(target->recv_cq);
goto out;
}

ib_req_notify_cq(target->recv_cq, IB_CQ_NEXT_COMP);

init_attr->event_handler = srp_qp_event;
init_attr->cap.max_send_wr = SRP_SQ_SIZE;
Expand All @@ -243,20 +252,22 @@ static int srp_create_target_ib(struct srp_target_port *target)
init_attr->cap.max_send_sge = 1;
init_attr->sq_sig_type = IB_SIGNAL_ALL_WR;
init_attr->qp_type = IB_QPT_RC;
init_attr->send_cq = target->cq;
init_attr->recv_cq = target->cq;
init_attr->send_cq = target->send_cq;
init_attr->recv_cq = target->recv_cq;

target->qp = ib_create_qp(target->srp_host->srp_dev->pd, init_attr);
if (IS_ERR(target->qp)) {
ret = PTR_ERR(target->qp);
ib_destroy_cq(target->cq);
ib_destroy_cq(target->send_cq);
ib_destroy_cq(target->recv_cq);
goto out;
}

ret = srp_init_qp(target, target->qp);
if (ret) {
ib_destroy_qp(target->qp);
ib_destroy_cq(target->cq);
ib_destroy_cq(target->send_cq);
ib_destroy_cq(target->recv_cq);
goto out;
}

Expand All @@ -270,7 +281,8 @@ static void srp_free_target_ib(struct srp_target_port *target)
int i;

ib_destroy_qp(target->qp);
ib_destroy_cq(target->cq);
ib_destroy_cq(target->send_cq);
ib_destroy_cq(target->recv_cq);

for (i = 0; i < SRP_RQ_SIZE; ++i)
srp_free_iu(target->srp_host, target->rx_ring[i]);
Expand Down Expand Up @@ -568,7 +580,9 @@ static int srp_reconnect_target(struct srp_target_port *target)
if (ret)
goto err;

while (ib_poll_cq(target->cq, 1, &wc) > 0)
while (ib_poll_cq(target->recv_cq, 1, &wc) > 0)
; /* nothing */
while (ib_poll_cq(target->send_cq, 1, &wc) > 0)
; /* nothing */

spin_lock_irq(target->scsi_host->host_lock);
Expand Down Expand Up @@ -851,7 +865,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
struct srp_iu *iu;
u8 opcode;

iu = target->rx_ring[wc->wr_id & ~SRP_OP_RECV];
iu = target->rx_ring[wc->wr_id];

dev = target->srp_host->srp_dev->dev;
ib_dma_sync_single_for_cpu(dev, iu->dma, target->max_ti_iu_len,
Expand Down Expand Up @@ -898,7 +912,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
DMA_FROM_DEVICE);
}

static void srp_completion(struct ib_cq *cq, void *target_ptr)
static void srp_recv_completion(struct ib_cq *cq, void *target_ptr)
{
struct srp_target_port *target = target_ptr;
struct ib_wc wc;
Expand All @@ -907,17 +921,31 @@ static void srp_completion(struct ib_cq *cq, void *target_ptr)
while (ib_poll_cq(cq, 1, &wc) > 0) {
if (wc.status) {
shost_printk(KERN_ERR, target->scsi_host,
PFX "failed %s status %d\n",
wc.wr_id & SRP_OP_RECV ? "receive" : "send",
PFX "failed receive status %d\n",
wc.status);
target->qp_in_error = 1;
break;
}

if (wc.wr_id & SRP_OP_RECV)
srp_handle_recv(target, &wc);
else
++target->tx_tail;
srp_handle_recv(target, &wc);
}
}

static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
{
struct srp_target_port *target = target_ptr;
struct ib_wc wc;

while (ib_poll_cq(cq, 1, &wc) > 0) {
if (wc.status) {
shost_printk(KERN_ERR, target->scsi_host,
PFX "failed send status %d\n",
wc.status);
target->qp_in_error = 1;
break;
}

++target->tx_tail;
}
}

Expand All @@ -930,7 +958,7 @@ static int __srp_post_recv(struct srp_target_port *target)
int ret;

next = target->rx_head & (SRP_RQ_SIZE - 1);
wr.wr_id = next | SRP_OP_RECV;
wr.wr_id = next;
iu = target->rx_ring[next];

list.addr = iu->dma;
Expand Down Expand Up @@ -970,6 +998,8 @@ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
{
s32 min = (req_type == SRP_REQ_TASK_MGMT) ? 1 : 2;

srp_send_completion(target->send_cq, target);

if (target->tx_head - target->tx_tail >= SRP_SQ_SIZE)
return NULL;

Expand Down
6 changes: 2 additions & 4 deletions drivers/infiniband/ulp/srp/ib_srp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,6 @@ enum {
SRP_RQ_SHIFT = 6,
SRP_RQ_SIZE = 1 << SRP_RQ_SHIFT,
SRP_SQ_SIZE = SRP_RQ_SIZE - 1,
SRP_CQ_SIZE = SRP_SQ_SIZE + SRP_RQ_SIZE,

SRP_TAG_TSK_MGMT = 1 << (SRP_RQ_SHIFT + 1),

Expand All @@ -69,8 +68,6 @@ enum {
SRP_FMR_DIRTY_SIZE = SRP_FMR_POOL_SIZE / 4
};

#define SRP_OP_RECV (1 << 31)

enum srp_target_state {
SRP_TARGET_LIVE,
SRP_TARGET_CONNECTING,
Expand Down Expand Up @@ -133,7 +130,8 @@ struct srp_target_port {
int path_query_id;

struct ib_cm_id *cm_id;
struct ib_cq *cq;
struct ib_cq *recv_cq;
struct ib_cq *send_cq;
struct ib_qp *qp;

int max_ti_iu_len;
Expand Down

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