[dpdk-dev,1/2] event/sw: code refractor to reduce the fetch stall
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Commit Message
With rearranging the code to prefetch the contents before
loop check increases performance from single and multistage
atomic pipeline.
Signed-off-by: Vipin Varghese <vipin.varghese@intel.com>
---
drivers/event/sw/sw_evdev_scheduler.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
Comments
-----Original Message-----
> Date: Fri, 2 Mar 2018 01:04:59 +0530
> From: Vipin Varghese <vipin.varghese@intel.com>
> To: dev@dpdk.org, harry.van.haaren@intel.com
> CC: Vipin Varghese <vipin.varghese@intel.com>
> Subject: [dpdk-dev] [PATCH 1/2] event/sw: code refractor to reduce the
> fetch stall
> X-Mailer: git-send-email 2.7.4
>
> With rearranging the code to prefetch the contents before
> loop check increases performance from single and multistage
> atomic pipeline.
>
> Signed-off-by: Vipin Varghese <vipin.varghese@intel.com>
Harry,
Can you review this patches(1/1 and 1/2)so that I can include it in RC1 pull
request.
Hey,
> -----Original Message-----
> From: Varghese, Vipin
> Sent: Thursday, March 1, 2018 7:35 PM
> To: dev@dpdk.org; Van Haaren, Harry <harry.van.haaren@intel.com>
> Cc: Varghese, Vipin <vipin.varghese@intel.com>
> Subject: [PATCH 1/2] event/sw: code refractor to reduce the fetch stall
>
> With rearranging the code to prefetch the contents before
> loop check increases performance from single and multistage
> atomic pipeline.
>
> Signed-off-by: Vipin Varghese <vipin.varghese@intel.com>
There seems to be a compilation issue with this, see "const" in flow_id.
The flow_id variable is updated later, so it can't be marked const.
After the compilation fix, I see a small performance improvement here,
so you can include my Ack for V2 of this patch:
Acked-by: Harry van Haaren <harry.van.haaren@intel.com
> ---
> drivers/event/sw/sw_evdev_scheduler.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/event/sw/sw_evdev_scheduler.c
> b/drivers/event/sw/sw_evdev_scheduler.c
> index e3a41e0..70d1970 100644
> --- a/drivers/event/sw/sw_evdev_scheduler.c
> +++ b/drivers/event/sw/sw_evdev_scheduler.c
> @@ -44,12 +44,13 @@ sw_schedule_atomic_to_cq(struct sw_evdev *sw, struct
> sw_qid * const qid,
> uint32_t qid_id = qid->id;
>
> iq_dequeue_burst(sw, &qid->iq[iq_num], qes, count);
> - for (i = 0; i < count; i++) {
> - const struct rte_event *qe = &qes[i];
> - const uint16_t flow_id = SW_HASH_FLOWID(qes[i].flow_id);
> - struct sw_fid_t *fid = &qid->fids[flow_id];
> - int cq = fid->cq;
>
> + const struct rte_event *qe = &qes[0];
> + const uint16_t flow_id = SW_HASH_FLOWID(qes[0].flow_id);
^^^^^^ remove the const here.
@@ -44,12 +44,13 @@ sw_schedule_atomic_to_cq(struct sw_evdev *sw, struct sw_qid * const qid,
uint32_t qid_id = qid->id;
iq_dequeue_burst(sw, &qid->iq[iq_num], qes, count);
- for (i = 0; i < count; i++) {
- const struct rte_event *qe = &qes[i];
- const uint16_t flow_id = SW_HASH_FLOWID(qes[i].flow_id);
- struct sw_fid_t *fid = &qid->fids[flow_id];
- int cq = fid->cq;
+ const struct rte_event *qe = &qes[0];
+ const uint16_t flow_id = SW_HASH_FLOWID(qes[0].flow_id);
+ struct sw_fid_t *fid = &qid->fids[flow_id];
+ int cq = fid->cq;
+
+ for (i = 0; i < count; i++) {
if (cq < 0) {
uint32_t cq_idx = qid->cq_next_tx++;
if (qid->cq_next_tx == qid->cq_num_mapped_cqs)
@@ -101,6 +102,13 @@ sw_schedule_atomic_to_cq(struct sw_evdev *sw, struct sw_qid * const qid,
&sw->cq_ring_space[cq]);
p->cq_buf_count = 0;
}
+
+ if (likely(i+1 < count)) {
+ qe = (qes + i + 1);
+ flow_id = SW_HASH_FLOWID(qes[i + 1].flow_id);
+ fid = &qid->fids[flow_id];
+ cq = fid->cq;
+ }
}
iq_put_back(sw, &qid->iq[iq_num], blocked_qes, nb_blocked);