To protect against CPU over utilization when guest performs unneeded
busy waiting loop on an empty CQ.
Signed-off-by: Yuval Shaia <yuval.sh...@oracle.com>
---
hw/rdma/rdma_backend.c | 11 +++++++----
hw/rdma/rdma_backend.h | 2 +-
hw/rdma/rdma_rm.c | 1 +
hw/rdma/rdma_rm_defs.h | 6 +++++-
hw/rdma/vmw/pvrdma_qp_ops.c | 24 +++++++++++++++++++++++-
5 files changed, 37 insertions(+), 7 deletions(-)
diff --git a/hw/rdma/rdma_backend.c b/hw/rdma/rdma_backend.c
index 2f6372f8f0..b7d6afb5da 100644
--- a/hw/rdma/rdma_backend.c
+++ b/hw/rdma/rdma_backend.c
@@ -64,9 +64,9 @@ static inline void complete_work(enum ibv_wc_status status,
uint32_t vendor_err,
comp_handler(ctx, &wc);
}
-static void rdma_poll_cq(RdmaDeviceResources *rdma_dev_res, struct ibv_cq
*ibcq)
+static int rdma_poll_cq(RdmaDeviceResources *rdma_dev_res, struct ibv_cq *ibcq)
{
- int i, ne;
+ int i, ne, total_ne = 0;
BackendCtx *bctx;
struct ibv_wc wc[2];
@@ -76,6 +76,7 @@ static void rdma_poll_cq(RdmaDeviceResources *rdma_dev_res,
struct ibv_cq *ibcq)
trace_rdma_poll_cq(ne, ibcq);
for (i = 0; i < ne; i++) {
+ total_ne++;
bctx = rdma_rm_get_cqe_ctx(rdma_dev_res, wc[i].wr_id);
if (unlikely(!bctx)) {
rdma_error_report("No matching ctx for req %"PRId64,
@@ -93,6 +94,8 @@ static void rdma_poll_cq(RdmaDeviceResources *rdma_dev_res,
struct ibv_cq *ibcq)
if (ne < 0) {
rdma_error_report("ibv_poll_cq fail, rc=%d, errno=%d", ne, errno);
}
+
+ return total_ne;
}
static void *comp_handler_thread(void *arg)
@@ -267,9 +270,9 @@ int rdma_backend_query_port(RdmaBackendDev *backend_dev,
return 0;
}
-void rdma_backend_poll_cq(RdmaDeviceResources *rdma_dev_res, RdmaBackendCQ *cq)
+int rdma_backend_poll_cq(RdmaDeviceResources *rdma_dev_res, RdmaBackendCQ *cq)
{
- rdma_poll_cq(rdma_dev_res, cq->ibcq);
+ return rdma_poll_cq(rdma_dev_res, cq->ibcq);
}
static GHashTable *ah_hash;
diff --git a/hw/rdma/rdma_backend.h b/hw/rdma/rdma_backend.h
index 5114c90e67..36305cd148 100644
--- a/hw/rdma/rdma_backend.h
+++ b/hw/rdma/rdma_backend.h
@@ -85,7 +85,7 @@ void rdma_backend_destroy_mr(RdmaBackendMR *mr);
int rdma_backend_create_cq(RdmaBackendDev *backend_dev, RdmaBackendCQ *cq,
int cqe);
void rdma_backend_destroy_cq(RdmaBackendCQ *cq);
-void rdma_backend_poll_cq(RdmaDeviceResources *rdma_dev_res, RdmaBackendCQ
*cq);
+int rdma_backend_poll_cq(RdmaDeviceResources *rdma_dev_res, RdmaBackendCQ *cq);
int rdma_backend_create_qp(RdmaBackendQP *qp, uint8_t qp_type,
RdmaBackendPD *pd, RdmaBackendCQ *scq,
diff --git a/hw/rdma/rdma_rm.c b/hw/rdma/rdma_rm.c
index 64c6ea1a4e..1ba77ac42c 100644
--- a/hw/rdma/rdma_rm.c
+++ b/hw/rdma/rdma_rm.c
@@ -261,6 +261,7 @@ int rdma_rm_alloc_cq(RdmaDeviceResources *dev_res,
RdmaBackendDev *backend_dev,
if (!cq) {
return -ENOMEM;
}
+ atomic_set(&cq->missing_cqe, 0);
cq->opaque = opaque;
cq->notify = CNT_CLEAR;
diff --git a/hw/rdma/rdma_rm_defs.h b/hw/rdma/rdma_rm_defs.h
index 0ba61d1838..08692e87d4 100644
--- a/hw/rdma/rdma_rm_defs.h
+++ b/hw/rdma/rdma_rm_defs.h
@@ -34,7 +34,9 @@
#define MAX_QP_INIT_RD_ATOM 16
#define MAX_AH 64
-#define MAX_RM_TBL_NAME 16
+#define MAX_RM_TBL_NAME 16
+#define MAX_CONSEQ_EMPTY_POLL_CQ 2048 /* considered as error above this */
+
typedef struct RdmaRmResTbl {
char name[MAX_RM_TBL_NAME];
QemuMutex lock;
@@ -59,6 +61,8 @@ typedef struct RdmaRmCQ {
RdmaBackendCQ backend_cq;
void *opaque;
CQNotificationType notify;
+ int missing_cqe;
+ int conseq_empty_poll;
} RdmaRmCQ;
/* MR (DMA region) */
diff --git a/hw/rdma/vmw/pvrdma_qp_ops.c b/hw/rdma/vmw/pvrdma_qp_ops.c
index 16db726dac..5d650a4943 100644
--- a/hw/rdma/vmw/pvrdma_qp_ops.c
+++ b/hw/rdma/vmw/pvrdma_qp_ops.c
@@ -60,6 +60,8 @@ static int pvrdma_post_cqe(PVRDMADev *dev, uint32_t cq_handle,
return -EINVAL;
}
+ atomic_dec(&cq->missing_cqe);
+
ring = (PvrdmaRing *)cq->opaque;
/* Step #1: Put CQE on CQ ring */
@@ -141,12 +143,15 @@ void pvrdma_qp_send(PVRDMADev *dev, uint32_t qp_handle)
PvrdmaRing *ring;
int sgid_idx;
union ibv_gid *sgid;
+ RdmaRmCQ *cq;
qp = rdma_rm_get_qp(&dev->rdma_dev_res, qp_handle);
if (unlikely(!qp)) {
return;
}
+ cq = rdma_rm_get_cq(&dev->rdma_dev_res, qp->send_cq_handle);
+
ring = (PvrdmaRing *)qp->opaque;
wqe = (struct PvrdmaSqWqe *)pvrdma_ring_next_elem_read(ring);
@@ -186,6 +191,7 @@ void pvrdma_qp_send(PVRDMADev *dev, uint32_t qp_handle)
continue;
}
+ atomic_inc(&cq->missing_cqe);
rdma_backend_post_send(&dev->backend_dev, &qp->backend_qp, qp->qp_type,
(struct ibv_sge *)&wqe->sge[0],
wqe->hdr.num_sge,
sgid_idx, sgid,
@@ -204,12 +210,15 @@ void pvrdma_qp_recv(PVRDMADev *dev, uint32_t qp_handle)
RdmaRmQP *qp;
PvrdmaRqWqe *wqe;
PvrdmaRing *ring;
+ RdmaRmCQ *cq;
qp = rdma_rm_get_qp(&dev->rdma_dev_res, qp_handle);
if (unlikely(!qp)) {
return;
}
+ cq = rdma_rm_get_cq(&dev->rdma_dev_res, qp->recv_cq_handle);
+
ring = &((PvrdmaRing *)qp->opaque)[1];
wqe = (struct PvrdmaRqWqe *)pvrdma_ring_next_elem_read(ring);
@@ -231,6 +240,7 @@ void pvrdma_qp_recv(PVRDMADev *dev, uint32_t qp_handle)
continue;
}
+ atomic_inc(&cq->missing_cqe);
rdma_backend_post_recv(&dev->backend_dev, &dev->rdma_dev_res,
&qp->backend_qp, qp->qp_type,
(struct ibv_sge *)&wqe->sge[0],
wqe->hdr.num_sge,
@@ -245,11 +255,23 @@ void pvrdma_qp_recv(PVRDMADev *dev, uint32_t qp_handle)
void pvrdma_cq_poll(RdmaDeviceResources *dev_res, uint32_t cq_handle)
{
RdmaRmCQ *cq;
+ int polled;
cq = rdma_rm_get_cq(dev_res, cq_handle);
if (!cq) {
return;
}
- rdma_backend_poll_cq(dev_res, &cq->backend_cq);
+ polled = rdma_backend_poll_cq(dev_res, &cq->backend_cq);
+ if (!polled) {
+ if (cq->conseq_empty_poll == MAX_CONSEQ_EMPTY_POLL_CQ) {
+ rdma_warn_report("%d consequtive empty polls from CQ %d, missing
cqe %d",
+ cq->conseq_empty_poll, cq_handle,
+ atomic_read(&cq->missing_cqe));
+ cq->conseq_empty_poll = 0;
+ }
+ cq->conseq_empty_poll++;
+ } else {
+ cq->conseq_empty_poll = 0;
+ }
}
--
2.17.2
