From: Artemy Kovalyov <artemyko@xxxxxxxxxxxx>
When regular CQ attempts to generate a CQE and the CQ is already full
overflow occurs and async error is generated.
On CQ created with IBV_CREATE_CQ_ATTR_IGNORE_OVERRUN flag overflow check
is disabled, error is never generated and CQE always will be written to
next entry.
Shortening fast-path message receive treatment allows low-latency
application to achieve better performance.
Signed-off-by: Artemy Kovalyov <artemyko@xxxxxxxxxxxx>
Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxxxx>
---
libibverbs/cmd_cq.c | 3 +++
libibverbs/man/ibv_create_cq_ex.3 | 1 +
libibverbs/verbs.h | 1 +
3 files changed, 5 insertions(+)
diff --git a/libibverbs/cmd_cq.c b/libibverbs/cmd_cq.c
index 73cd2f2..7669518 100644
--- a/libibverbs/cmd_cq.c
+++ b/libibverbs/cmd_cq.c
@@ -142,6 +142,9 @@ int ibv_cmd_create_cq_ex(struct ibv_context *context,
if (cq_attr->wc_flags & IBV_WC_EX_WITH_COMPLETION_TIMESTAMP)
flags |= IB_UVERBS_CQ_FLAGS_TIMESTAMP_COMPLETION;
+ if (cq_attr->flags & IBV_CREATE_CQ_ATTR_IGNORE_OVERRUN)
+ flags |= IB_UVERBS_CQ_FLAGS_IGNORE_OVERRUN;
+
return ibv_icmd_create_cq(context, cq_attr->cqe, cq_attr->channel,
cq_attr->comp_vector, flags,
ibv_cq_ex_to_cq(cq), cmdb);
diff --git a/libibverbs/man/ibv_create_cq_ex.3 b/libibverbs/man/ibv_create_cq_ex.3
index 2abdbe4..5d39457 100644
--- a/libibverbs/man/ibv_create_cq_ex.3
+++ b/libibverbs/man/ibv_create_cq_ex.3
@@ -52,6 +52,7 @@ enum ibv_cq_init_attr_mask {
enum ibv_create_cq_attr_flags {
IBV_CREATE_CQ_ATTR_SINGLE_THREADED = 1 << 0, /* This CQ is used from a single threaded, thus no locking is required */
+ IBV_CREATE_CQ_ATTR_IGNORE_OVERRUN = 1 << 1, /* This CQ will not pass to error state if overrun, CQE always will be written to next entry */
};
.SH "Polling an extended CQ"
diff --git a/libibverbs/verbs.h b/libibverbs/verbs.h
index ad44c7d..80b8414 100644
--- a/libibverbs/verbs.h
+++ b/libibverbs/verbs.h
@@ -1717,6 +1717,7 @@ enum ibv_cq_init_attr_mask {
enum ibv_create_cq_attr_flags {
IBV_CREATE_CQ_ATTR_SINGLE_THREADED = 1 << 0,
+ IBV_CREATE_CQ_ATTR_IGNORE_OVERRUN = 1 << 1,
};
struct ibv_cq_init_attr_ex {
--
1.8.3.1
