[PATCH v3 1/2] net/iavf: remove PHC polling from Rx datapath

Soumyadeep Hore
2026-04-06T08:51:09Z

Remove periodic PHC read/update checks from scalar and vector flex
RX paths, keeping timestamp conversion based on queue PHC state.

This avoids hot-path PHC polling overhead and preserves the latency
fix for RX timestamp-enabled traffic.

Signed-off-by: Soumyadeep Hore <soumyadeep.hore@intel.com>
---
drivers/net/intel/iavf/iavf_rxtx.c | 34 -------------------
drivers/net/intel/iavf/iavf_rxtx_vec_avx2.c | 24 ++-----------
drivers/net/intel/iavf/iavf_rxtx_vec_avx512.c | 26 ++------------
3 files changed, 6 insertions(+), 78 deletions(-)

diff --git a/drivers/net/intel/iavf/iavf_rxtx.c b/drivers/net/intel/iavf/iavf_rxtx.c
index 4ff6c18dc4..fabccc89bf 100644
--- a/drivers/net/intel/iavf/iavf_rxtx.c
+++ b/drivers/net/intel/iavf/iavf_rxtx.c
@@ -1507,16 +1507,6 @@ iavf_recv_pkts_flex_rxd(void *rx_queue,
rx_ring = rxq->rx_flex_ring;
ptype_tbl = rxq->iavf_vsi->adapter->ptype_tbl;

- if (rxq->offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP) {
- uint64_t sw_cur_time = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);
-
- if (sw_cur_time - rxq->hw_time_update > 4) {
- if (iavf_get_phc_time(rxq))
- PMD_DRV_LOG(ERR, "get physical time failed");
- rxq->hw_time_update = sw_cur_time;
- }
- }
-
while (nb_rx < nb_pkts) {
rxdp = &rx_ring[rx_id];
rx_stat_err0 = rte_le_to_cpu_16(rxdp->wb.status_error0);
@@ -1585,7 +1575,6 @@ iavf_recv_pkts_flex_rxd(void *rx_queue,
rte_le_to_cpu_32(rxd.wb.flex_ts.ts_high));

rxq->phc_time = ts_ns;
- rxq->hw_time_update = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);

*RTE_MBUF_DYNFIELD(rxm,
iavf_timestamp_dynfield_offset,
@@ -1627,16 +1616,6 @@ iavf_recv_scattered_pkts_flex_rxd(void *rx_queue, struct rte_mbuf **rx_pkts,
volatile union ci_rx_flex_desc *rxdp;
const uint32_t *ptype_tbl = rxq->iavf_vsi->adapter->ptype_tbl;

- if (rxq->offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP) {
- uint64_t sw_cur_time = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);
-
- if (sw_cur_time - rxq->hw_time_update > 4) {
- if (iavf_get_phc_time(rxq))
- PMD_DRV_LOG(ERR, "get physical time failed");
- rxq->hw_time_update = sw_cur_time;
- }
- }
-
while (nb_rx < nb_pkts) {
rxdp = &rx_ring[rx_id];
rx_stat_err0 = rte_le_to_cpu_16(rxdp->wb.status_error0);
@@ -1755,7 +1734,6 @@ iavf_recv_scattered_pkts_flex_rxd(void *rx_queue, struct rte_mbuf **rx_pkts,
rte_le_to_cpu_32(rxd.wb.flex_ts.ts_high));

rxq->phc_time = ts_ns;
- rxq->hw_time_update = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);

*RTE_MBUF_DYNFIELD(first_seg,
iavf_timestamp_dynfield_offset,
@@ -1969,16 +1947,6 @@ iavf_rx_scan_hw_ring_flex_rxd(struct ci_rx_queue *rxq,
if (!(stat_err0 & (1 << IAVF_RX_FLEX_DESC_STATUS0_DD_S)))
return 0;

- if (rxq->offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP) {
- uint64_t sw_cur_time = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);
-
- if (sw_cur_time - rxq->hw_time_update > 4) {
- if (iavf_get_phc_time(rxq))
- PMD_DRV_LOG(ERR, "get physical time failed");
- rxq->hw_time_update = sw_cur_time;
- }
- }
-
/* Scan LOOK_AHEAD descriptors at a time to determine which
* descriptors reference packets that are ready to be received.
*/
@@ -2041,8 +2009,6 @@ iavf_rx_scan_hw_ring_flex_rxd(struct ci_rx_queue *rxq,
rte_le_to_cpu_32(rxdp[j].wb.flex_ts.ts_high));

rxq->phc_time = ts_ns;
- rxq->hw_time_update = rte_get_timer_cycles() /
- (rte_get_timer_hz() / 1000);

*RTE_MBUF_DYNFIELD(mb,
iavf_timestamp_dynfield_offset,
diff --git a/drivers/net/intel/iavf/iavf_rxtx_vec_avx2.c b/drivers/net/intel/iavf/iavf_rxtx_vec_avx2.c
index db0462f0f5..c91123ead4 100644
--- a/drivers/net/intel/iavf/iavf_rxtx_vec_avx2.c
+++ b/drivers/net/intel/iavf/iavf_rxtx_vec_avx2.c
@@ -514,19 +514,8 @@ _iavf_recv_raw_pkts_vec_avx2_flex_rxd(struct ci_rx_queue *rxq,
if (!(rxdp->wb.status_error0 &
rte_cpu_to_le_32(1 << IAVF_RX_FLEX_DESC_STATUS0_DD_S)))
return 0;
- bool is_tsinit = false;
uint8_t inflection_point = 0;
__m256i hw_low_last = _mm256_set_epi32(0, 0, 0, 0, 0, 0, 0, rxq->phc_time);
- if (rxq->offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP) {
- uint64_t sw_cur_time = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);
-
- if (unlikely(sw_cur_time - rxq->hw_time_update > 4)) {
- hw_low_last = _mm256_setzero_si256();
- is_tsinit = 1;
- } else {
- hw_low_last = _mm256_set_epi32(0, 0, 0, 0, 0, 0, 0, rxq->phc_time);
- }
- }

/* constants used in processing loop */
const __m256i crc_adjust =
@@ -1152,14 +1141,9 @@ _iavf_recv_raw_pkts_vec_avx2_flex_rxd(struct ci_rx_queue *rxq,
*RTE_MBUF_DYNFIELD(rx_pkts[i + 7],
iavf_timestamp_dynfield_offset, uint32_t *) = _mm256_extract_epi32(ts_low1, 7);

- if (unlikely(is_tsinit)) {
- uint32_t in_timestamp;
- if (iavf_get_phc_time(rxq))
- PMD_DRV_LOG(ERR, "get physical time failed");
- in_timestamp = *RTE_MBUF_DYNFIELD(rx_pkts[i + 0],
- iavf_timestamp_dynfield_offset, uint32_t *);
- rxq->phc_time = iavf_tstamp_convert_32b_64b(rxq->phc_time, in_timestamp);
- }
+ rxq->phc_time = iavf_tstamp_convert_32b_64b(rxq->phc_time,
+ *RTE_MBUF_DYNFIELD(rx_pkts[i + 0],
+ iavf_timestamp_dynfield_offset, uint32_t *));

*RTE_MBUF_DYNFIELD(rx_pkts[i + 0],
iavf_timestamp_dynfield_offset + 4, uint32_t *) = (uint32_t)(rxq->phc_time >> 32);
@@ -1388,8 +1372,6 @@ _iavf_recv_raw_pkts_vec_avx2_flex_rxd(struct ci_rx_queue *rxq,
PMD_DRV_LOG(ERR, "invalid inflection point for rx timestamp");
break;
}
-
- rxq->hw_time_update = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);
}
if (burst != IAVF_VPMD_DESCS_PER_LOOP_WIDE)
break;
diff --git a/drivers/net/intel/iavf/iavf_rxtx_vec_avx512.c b/drivers/net/intel/iavf/iavf_rxtx_vec_avx512.c
index 4e8bf94fa0..a7c0a02eba 100644
--- a/drivers/net/intel/iavf/iavf_rxtx_vec_avx512.c
+++ b/drivers/net/intel/iavf/iavf_rxtx_vec_avx512.c
@@ -615,19 +615,7 @@ _iavf_recv_raw_pkts_vec_avx512_flex_rxd(struct ci_rx_queue *rxq,

#ifdef IAVF_RX_TS_OFFLOAD
uint8_t inflection_point = 0;
- bool is_tsinit = false;
__m256i hw_low_last = _mm256_set_epi32(0, 0, 0, 0, 0, 0, 0, (uint32_t)rxq->phc_time);
-
- if (rxq->offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP) {
- uint64_t sw_cur_time = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);
-
- if (unlikely(sw_cur_time - rxq->hw_time_update > 4)) {
- hw_low_last = _mm256_setzero_si256();
- is_tsinit = 1;
- } else {
- hw_low_last = _mm256_set_epi32(0, 0, 0, 0, 0, 0, 0, (uint32_t)rxq->phc_time);
- }
- }
#endif

/* constants used in processing loop */
@@ -1343,15 +1331,9 @@ _iavf_recv_raw_pkts_vec_avx512_flex_rxd(struct ci_rx_queue *rxq,
*RTE_MBUF_DYNFIELD(rx_pkts[i + 7],
iavf_timestamp_dynfield_offset, uint32_t *) = _mm256_extract_epi32(ts_low1, 7);

- if (unlikely(is_tsinit)) {
- uint32_t in_timestamp;
-
- if (iavf_get_phc_time(rxq))
- PMD_DRV_LOG(ERR, "get physical time failed");
- in_timestamp = *RTE_MBUF_DYNFIELD(rx_pkts[i + 0],
- iavf_timestamp_dynfield_offset, uint32_t *);
- rxq->phc_time = iavf_tstamp_convert_32b_64b(rxq->phc_time, in_timestamp);
- }
+ rxq->phc_time = iavf_tstamp_convert_32b_64b(rxq->phc_time,
+ *RTE_MBUF_DYNFIELD(rx_pkts[i + 0],
+ iavf_timestamp_dynfield_offset, uint32_t *));

*RTE_MBUF_DYNFIELD(rx_pkts[i + 0],
iavf_timestamp_dynfield_offset + 4, uint32_t *) = (uint32_t)(rxq->phc_time >> 32);
@@ -1584,8 +1566,6 @@ _iavf_recv_raw_pkts_vec_avx512_flex_rxd(struct ci_rx_queue *rxq,
PMD_DRV_LOG(ERR, "invalid inflection point for rx timestamp");
break;
}
-
- rxq->hw_time_update = rte_get_timer_cycles() / (rte_get_timer_hz() / 1000);
}
#endif
if (burst != IAVF_VPMD_DESCS_PER_LOOP_WIDE)
--
2.47.1