On Tue, Jun 19, 2018 at 4:49 AM Vijay Immanuel <vijayi@xxxxxxxxxxxxxxxxx> wrote:
>
> A QP must use the same NIC TX queue to maintain packet order. The TX
> queue is usually selected based on the core from which the transmit
> was originated.
> Assign QPs to cores to better spread traffic across TX queues. This
> requires scheduling the tasklets in the cpu assigned to the QP. The
> transmit cpu is selected based on the comp_vector for the QP's scq.
>
> Signed-off-by: Vijay Immanuel <vijayi@xxxxxxxxxxxxxxxxx>
> ---
> drivers/infiniband/sw/rxe/rxe_comp.c | 8 +------
> drivers/infiniband/sw/rxe/rxe_cq.c | 1 +
> drivers/infiniband/sw/rxe/rxe_qp.c | 6 ++---
> drivers/infiniband/sw/rxe/rxe_resp.c | 8 +------
> drivers/infiniband/sw/rxe/rxe_task.c | 45 ++++++++++++++++++++++++++++++++---
> drivers/infiniband/sw/rxe/rxe_task.h | 7 +++++-
> drivers/infiniband/sw/rxe/rxe_verbs.c | 3 +--
> drivers/infiniband/sw/rxe/rxe_verbs.h | 1 +
> 8 files changed, 56 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
> index 6cdc40e..189f80e 100644
> --- a/drivers/infiniband/sw/rxe/rxe_comp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_comp.c
> @@ -149,14 +149,8 @@ void retransmit_timer(struct timer_list *t)
> void rxe_comp_queue_pkt(struct rxe_dev *rxe, struct rxe_qp *qp,
> struct sk_buff *skb)
> {
> - int must_sched;
> -
> skb_queue_tail(&qp->resp_pkts, skb);
> -
> - must_sched = skb_queue_len(&qp->resp_pkts) > 1;
> - if (must_sched != 0)
> - rxe_counter_inc(rxe, RXE_CNT_COMPLETER_SCHED);
> - rxe_run_task(&qp->comp.task, must_sched);
> + rxe_run_task(&qp->comp.task, 1);
> }
>
> static inline enum comp_state get_wqe(struct rxe_qp *qp,
> diff --git a/drivers/infiniband/sw/rxe/rxe_cq.c b/drivers/infiniband/sw/rxe/rxe_cq.c
> index 2ee4b08..ac7c5d0 100644
> --- a/drivers/infiniband/sw/rxe/rxe_cq.c
> +++ b/drivers/infiniband/sw/rxe/rxe_cq.c
> @@ -106,6 +106,7 @@ int rxe_cq_from_init(struct rxe_dev *rxe, struct rxe_cq *cq, int cqe,
> cq->is_user = 1;
>
> cq->is_dying = false;
> + cq->comp_vector = comp_vector;
What does this mean in RXE since we don't have control on the HW?
>
> tasklet_init(&cq->comp_task, rxe_send_complete, (unsigned long)cq);
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c
> index b9f7aa1..58204c8 100644
> --- a/drivers/infiniband/sw/rxe/rxe_qp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_qp.c
> @@ -260,9 +260,9 @@ static int rxe_qp_init_req(struct rxe_dev *rxe, struct rxe_qp *qp,
> spin_lock_init(&qp->sq.sq_lock);
> skb_queue_head_init(&qp->req_pkts);
>
> - rxe_init_task(rxe, &qp->req.task, qp,
> + rxe_init_task(rxe, &qp->req.task, qp->scq->comp_vector, qp,
> rxe_requester, "req");
> - rxe_init_task(rxe, &qp->comp.task, qp,
> + rxe_init_task(rxe, &qp->comp.task, qp->scq->comp_vector, qp,
> rxe_completer, "comp");
You bind all tasklets to the completion vector of the SCQ. I think it
makes bad use of this value since it is mentioned in the documentation
of create_cq() and applications shouldn't expect this.
>
> qp->qp_timeout_jiffies = 0; /* Can't be set for UD/UC in modify_qp */
> @@ -311,7 +311,7 @@ static int rxe_qp_init_resp(struct rxe_dev *rxe, struct rxe_qp *qp,
>
> skb_queue_head_init(&qp->resp_pkts);
>
> - rxe_init_task(rxe, &qp->resp.task, qp,
> + rxe_init_task(rxe, &qp->resp.task, qp->scq->comp_vector, qp,
> rxe_responder, "resp");
>
> qp->resp.opcode = OPCODE_NONE;
> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
> index 955ff3b..853ab49 100644
> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
> @@ -107,15 +107,9 @@ static char *resp_state_name[] = {
> void rxe_resp_queue_pkt(struct rxe_dev *rxe, struct rxe_qp *qp,
> struct sk_buff *skb)
> {
> - int must_sched;
> - struct rxe_pkt_info *pkt = SKB_TO_PKT(skb);
> -
> skb_queue_tail(&qp->req_pkts, skb);
>
> - must_sched = (pkt->opcode == IB_OPCODE_RC_RDMA_READ_REQUEST) ||
> - (skb_queue_len(&qp->req_pkts) > 1);
> -
> - rxe_run_task(&qp->resp.task, must_sched);
> + rxe_run_task(&qp->resp.task, 1);
> }
>
> static inline enum resp_states get_req(struct rxe_qp *qp,
> diff --git a/drivers/infiniband/sw/rxe/rxe_task.c b/drivers/infiniband/sw/rxe/rxe_task.c
> index 08f05ac..8b7cb97 100644
> --- a/drivers/infiniband/sw/rxe/rxe_task.c
> +++ b/drivers/infiniband/sw/rxe/rxe_task.c
> @@ -37,6 +37,8 @@
>
> #include "rxe_task.h"
>
> +static void rxe_run_task_local(void *data);
> +
> int __rxe_do_task(struct rxe_task *task)
>
> {
> @@ -63,6 +65,7 @@ void rxe_do_task(unsigned long data)
> struct rxe_task *task = (struct rxe_task *)data;
>
> spin_lock_irqsave(&task->state_lock, flags);
> + task->scheduled = false;
> switch (task->state) {
> case TASK_STATE_START:
> task->state = TASK_STATE_BUSY;
> @@ -108,20 +111,27 @@ void rxe_do_task(unsigned long data)
> pr_warn("%s failed with bad state %d\n", __func__,
> task->state);
> }
> +
> + if (!cont && task->scheduled)
> + tasklet_schedule(&task->tasklet);
> spin_unlock_irqrestore(&task->state_lock, flags);
> } while (cont);
>
> task->ret = ret;
> }
>
> -int rxe_init_task(void *obj, struct rxe_task *task,
> +int rxe_init_task(void *obj, struct rxe_task *task, int cpu,
> void *arg, int (*func)(void *), char *name)
> {
> + task->cpu = cpu;
> task->obj = obj;
> task->arg = arg;
> task->func = func;
> + task->csd.func = rxe_run_task_local;
> + task->csd.info = task;
> snprintf(task->name, sizeof(task->name), "%s", name);
> task->destroyed = false;
> + task->scheduled = false;
>
> tasklet_init(&task->tasklet, rxe_do_task, (unsigned long)task);
>
> @@ -151,15 +161,44 @@ void rxe_cleanup_task(struct rxe_task *task)
> tasklet_kill(&task->tasklet);
> }
>
> +static void rxe_run_task_local(void *data)
> +{
> + struct rxe_task *task = (struct rxe_task *)data;
> +
> + if (task->destroyed)
> + return;
> +
> + tasklet_schedule(&task->tasklet);
> +}
> +
> void rxe_run_task(struct rxe_task *task, int sched)
> {
> + int cpu;
> + unsigned long flags;
> +
> if (task->destroyed)
> return;
>
> - if (sched)
> + if (!sched) {
> + rxe_do_task((unsigned long)task);
> + return;
> + }
> +
> + spin_lock_irqsave(&task->state_lock, flags);
> + if (task->scheduled || task->state != TASK_STATE_START) {
> + task->scheduled = true;
> + spin_unlock_irqrestore(&task->state_lock, flags);
> + return;
> + }
> + task->scheduled = true;
> + spin_unlock_irqrestore(&task->state_lock, flags);
> +
> + cpu = get_cpu();
> + if (task->cpu == cpu || !cpu_online(task->cpu))
> tasklet_schedule(&task->tasklet);
> else
> - rxe_do_task((unsigned long)task);
> + smp_call_function_single_async(task->cpu, &task->csd);
> + put_cpu();
> }
>
> void rxe_disable_task(struct rxe_task *task)
> diff --git a/drivers/infiniband/sw/rxe/rxe_task.h b/drivers/infiniband/sw/rxe/rxe_task.h
> index 08ff42d..1470dee 100644
> --- a/drivers/infiniband/sw/rxe/rxe_task.h
> +++ b/drivers/infiniband/sw/rxe/rxe_task.h
> @@ -34,6 +34,8 @@
> #ifndef RXE_TASK_H
> #define RXE_TASK_H
>
> +#include <linux/smp.h>
> +
> enum {
> TASK_STATE_START = 0,
> TASK_STATE_BUSY = 1,
> @@ -48,13 +50,16 @@ enum {
> struct rxe_task {
> void *obj;
> struct tasklet_struct tasklet;
> + int cpu;
> int state;
> spinlock_t state_lock; /* spinlock for task state */
> void *arg;
> int (*func)(void *arg);
> + call_single_data_t csd;
> int ret;
> char name[16];
> bool destroyed;
> + bool scheduled;
> };
>
> /*
> @@ -62,7 +67,7 @@ struct rxe_task {
> * arg => parameter to pass to fcn
> * fcn => function to call until it returns != 0
> */
> -int rxe_init_task(void *obj, struct rxe_task *task,
> +int rxe_init_task(void *obj, struct rxe_task *task, int cpu,
> void *arg, int (*func)(void *), char *name);
>
> /* cleanup task */
> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
> index 73a00a1..addccc1 100644
> --- a/drivers/infiniband/sw/rxe/rxe_verbs.c
> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
> @@ -813,8 +813,7 @@ static int rxe_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
> }
>
> if (qp->is_user) {
> - /* Utilize process context to do protocol processing */
> - rxe_run_task(&qp->req.task, 0);
> + rxe_run_task(&qp->req.task, 1);
> return 0;
> } else
> return rxe_post_send_kernel(qp, wr, bad_wr);
This overrides the CPU that the application choose to run on. I'm not
sure that this is a good idea.
If you left this code unchanged you can trust on the application to
make a smart CPU selection and get the better utilization that you
want to get. What do you think?
> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
> index af1470d..6c6e8db 100644
> --- a/drivers/infiniband/sw/rxe/rxe_verbs.h
> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
> @@ -92,6 +92,7 @@ struct rxe_cq {
> u8 notify;
> bool is_dying;
> int is_user;
> + int comp_vector;
> struct tasklet_struct comp_task;
> };
>
> --
> 2.7.4
>
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