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From: Konstantin Ananyev <konstantin.ananyev@huawei.com>
To: huangdengdui <huangdengdui@huawei.com>, "dev@dpdk.org" <dev@dpdk.org>
CC: "wathsala.vithanage@arm.com" <wathsala.vithanage@arm.com>,
"stephen@networkplumber.org" <stephen@networkplumber.org>, "lihuisong (C)"
<lihuisong@huawei.com>, Fengchengwen <fengchengwen@huawei.com>, haijie
<haijie1@huawei.com>, liuyonglong <liuyonglong@huawei.com>
Subject: RE: [PATCH] examples/l3fwd: add option to set refetch offset
Thread-Topic: [PATCH] examples/l3fwd: add option to set refetch offset
Thread-Index: AQHbY0M+J3rwtDemskeud65RtItxhbNPEU3g
Date: Wed, 19 Feb 2025 16:44:12 +0000
Message-ID: <e514a9af829447c2965b3e2d5b2672fb@huawei.com>
References: <20241225075302.353013-1-huangdengdui@huawei.com>
<20250110093715.4044681-1-huangdengdui@huawei.com>
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> Subject: [PATCH] examples/l3fwd: add option to set refetch offset
I suppose it should be 'prefetch'.
=20
> The prefetch window depending on the HW platform. It is difficult to
> measure the prefetch window of a HW platform. Therefore, the prefetch
> offset option is added to change the prefetch window. User can adjust
> the refetch offset to achieve the best prefetch effect.
>=20
> In addition, this option is used only in the main loop.
I run few tests for fib,lpm,acl modes on my Intel ICX box.
Didn't notice any performance drop with that patch.
>=20
> Signed-off-by: Dengdui Huang <huangdengdui@huawei.com>
> ---
> examples/l3fwd/l3fwd.h | 6 ++-
> examples/l3fwd/l3fwd_acl_scalar.h | 6 +--
> examples/l3fwd/l3fwd_em.h | 18 ++++-----
> examples/l3fwd/l3fwd_em_hlm.h | 9 +++--
> examples/l3fwd/l3fwd_em_sequential.h | 60 ++++++++++++++++------------
> examples/l3fwd/l3fwd_fib.c | 21 +++++-----
> examples/l3fwd/l3fwd_lpm.h | 6 +--
> examples/l3fwd/l3fwd_lpm_neon.h | 45 ++++-----------------
> examples/l3fwd/main.c | 14 +++++++
> 9 files changed, 91 insertions(+), 94 deletions(-)
>=20
> diff --git a/examples/l3fwd/l3fwd.h b/examples/l3fwd/l3fwd.h
> index 0cce3406ee..2272fb2870 100644
> --- a/examples/l3fwd/l3fwd.h
> +++ b/examples/l3fwd/l3fwd.h
> @@ -39,8 +39,7 @@
>=20
> #define NB_SOCKETS 8
>=20
> -/* Configure how many packets ahead to prefetch, when reading packets */
> -#define PREFETCH_OFFSET 3
> +#define DEFAULT_PREFECH_OFFSET 4
>=20
> /* Used to mark destination port as 'invalid'. */
> #define BAD_PORT ((uint16_t)-1)
> @@ -119,6 +118,9 @@ extern uint32_t max_pkt_len;
> extern uint32_t nb_pkt_per_burst;
> extern uint32_t mb_mempool_cache_size;
>=20
> +/* Prefetch offset of packets processed by the main loop. */
> +extern uint16_t prefetch_offset;
> +
> /* Send burst of packets on an output interface */
> static inline int
> send_burst(struct lcore_conf *qconf, uint16_t n, uint16_t port)
> diff --git a/examples/l3fwd/l3fwd_acl_scalar.h b/examples/l3fwd/l3fwd_acl=
_scalar.h
> index cb22bb49aa..d00730ff25 100644
> --- a/examples/l3fwd/l3fwd_acl_scalar.h
> +++ b/examples/l3fwd/l3fwd_acl_scalar.h
> @@ -72,14 +72,14 @@ l3fwd_acl_prepare_acl_parameter(struct rte_mbuf **pkt=
s_in, struct acl_search_t *
> acl->num_ipv6 =3D 0;
>=20
> /* Prefetch first packets */
> - for (i =3D 0; i < PREFETCH_OFFSET && i < nb_rx; i++) {
> + for (i =3D 0; i < prefetch_offset && i < nb_rx; i++) {
> rte_prefetch0(rte_pktmbuf_mtod(
> pkts_in[i], void *));
> }
>=20
> - for (i =3D 0; i < (nb_rx - PREFETCH_OFFSET); i++) {
> + for (i =3D 0; i < (nb_rx - prefetch_offset); i++) {
> rte_prefetch0(rte_pktmbuf_mtod(pkts_in[
> - i + PREFETCH_OFFSET], void *));
> + i + prefetch_offset], void *));
> l3fwd_acl_prepare_one_packet(pkts_in, acl, i);
> }
>=20
> diff --git a/examples/l3fwd/l3fwd_em.h b/examples/l3fwd/l3fwd_em.h
> index 1fee2e2e6c..3ef32c9053 100644
> --- a/examples/l3fwd/l3fwd_em.h
> +++ b/examples/l3fwd/l3fwd_em.h
> @@ -132,16 +132,16 @@ l3fwd_em_no_opt_send_packets(int nb_rx, struct rte_=
mbuf **pkts_burst,
> int32_t j;
>=20
> /* Prefetch first packets */
> - for (j =3D 0; j < PREFETCH_OFFSET && j < nb_rx; j++)
> + for (j =3D 0; j < prefetch_offset && j < nb_rx; j++)
> rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[j], void *));
>=20
> /*
> * Prefetch and forward already prefetched
> * packets.
> */
> - for (j =3D 0; j < (nb_rx - PREFETCH_OFFSET); j++) {
> + for (j =3D 0; j < (nb_rx - prefetch_offset); j++) {
> rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[
> - j + PREFETCH_OFFSET], void *));
> + j + prefetch_offset], void *));
> l3fwd_em_simple_forward(pkts_burst[j], portid, qconf);
> }
>=20
> @@ -161,16 +161,16 @@ l3fwd_em_no_opt_process_events(int nb_rx, struct rt=
e_event **events,
> int32_t j;
>=20
> /* Prefetch first packets */
> - for (j =3D 0; j < PREFETCH_OFFSET && j < nb_rx; j++)
> + for (j =3D 0; j < prefetch_offset && j < nb_rx; j++)
> rte_prefetch0(rte_pktmbuf_mtod(events[j]->mbuf, void *));
>=20
> /*
> * Prefetch and forward already prefetched
> * packets.
> */
> - for (j =3D 0; j < (nb_rx - PREFETCH_OFFSET); j++) {
> + for (j =3D 0; j < (nb_rx - prefetch_offset); j++) {
> rte_prefetch0(rte_pktmbuf_mtod(events[
> - j + PREFETCH_OFFSET]->mbuf, void *));
> + j + prefetch_offset]->mbuf, void *));
> l3fwd_em_simple_process(events[j]->mbuf, qconf);
> }
>=20
> @@ -188,15 +188,15 @@ l3fwd_em_no_opt_process_event_vector(struct rte_eve=
nt_vector *vec,
> int32_t i;
>=20
> /* Prefetch first packets */
> - for (i =3D 0; i < PREFETCH_OFFSET && i < vec->nb_elem; i++)
> + for (i =3D 0; i < prefetch_offset && i < vec->nb_elem; i++)
> rte_prefetch0(rte_pktmbuf_mtod(mbufs[i], void *));
>=20
> /*
> * Prefetch and forward already prefetched packets.
> */
> - for (i =3D 0; i < (vec->nb_elem - PREFETCH_OFFSET); i++) {
> + for (i =3D 0; i < (vec->nb_elem - prefetch_offset); i++) {
> rte_prefetch0(
> - rte_pktmbuf_mtod(mbufs[i + PREFETCH_OFFSET], void *));
> + rte_pktmbuf_mtod(mbufs[i + prefetch_offset], void *));
> dst_ports[i] =3D l3fwd_em_simple_process(mbufs[i], qconf);
> }
>=20
> diff --git a/examples/l3fwd/l3fwd_em_hlm.h b/examples/l3fwd/l3fwd_em_hlm.=
h
> index c1d819997a..764527962b 100644
> --- a/examples/l3fwd/l3fwd_em_hlm.h
> +++ b/examples/l3fwd/l3fwd_em_hlm.h
> @@ -190,7 +190,7 @@ l3fwd_em_process_packets(int nb_rx, struct rte_mbuf *=
*pkts_burst,
> */
> int32_t n =3D RTE_ALIGN_FLOOR(nb_rx, EM_HASH_LOOKUP_COUNT);
>=20
> - for (j =3D 0; j < EM_HASH_LOOKUP_COUNT && j < nb_rx; j++) {
> + for (j =3D 0; j < prefetch_offset && j < nb_rx; j++) {
> rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[j],
> struct rte_ether_hdr *) + 1);
> }
> @@ -207,7 +207,7 @@ l3fwd_em_process_packets(int nb_rx, struct rte_mbuf *=
*pkts_burst,
> l3_type =3D pkt_type & RTE_PTYPE_L3_MASK;
> tcp_or_udp =3D pkt_type & (RTE_PTYPE_L4_TCP | RTE_PTYPE_L4_UDP);
>=20
> - for (i =3D 0, pos =3D j + EM_HASH_LOOKUP_COUNT;
> + for (i =3D 0, pos =3D j + prefetch_offset;
> i < EM_HASH_LOOKUP_COUNT && pos < nb_rx; i++, pos++) {
> rte_prefetch0(rte_pktmbuf_mtod(
> pkts_burst[pos],
> @@ -277,6 +277,9 @@ l3fwd_em_process_events(int nb_rx, struct rte_event *=
*ev,
> for (j =3D 0; j < nb_rx; j++)
> pkts_burst[j] =3D ev[j]->mbuf;
>=20
> + for (i =3D 0; i < prefetch_offset && i < nb_rx; i++)
> + rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i], struct rte_ether_hdr *) =
+ 1);
> +
If there are no prefetches right now, probably no need to add new.
Or if you feel strongly about it - make it as a new patch.
> for (j =3D 0; j < n; j +=3D EM_HASH_LOOKUP_COUNT) {
>=20
> uint32_t pkt_type =3D RTE_PTYPE_L3_MASK |
> @@ -289,7 +292,7 @@ l3fwd_em_process_events(int nb_rx, struct rte_event *=
*ev,
> l3_type =3D pkt_type & RTE_PTYPE_L3_MASK;
> tcp_or_udp =3D pkt_type & (RTE_PTYPE_L4_TCP | RTE_PTYPE_L4_UDP);
>=20
> - for (i =3D 0, pos =3D j + EM_HASH_LOOKUP_COUNT;
> + for (i =3D 0, pos =3D j + prefetch_offset;
> i < EM_HASH_LOOKUP_COUNT && pos < nb_rx; i++, pos++) {
> rte_prefetch0(rte_pktmbuf_mtod(
> pkts_burst[pos],
> diff --git a/examples/l3fwd/l3fwd_em_sequential.h b/examples/l3fwd/l3fwd_=
em_sequential.h
> index 3a40b2e434..f2c6ceb7c0 100644
> --- a/examples/l3fwd/l3fwd_em_sequential.h
> +++ b/examples/l3fwd/l3fwd_em_sequential.h
> @@ -81,20 +81,19 @@ l3fwd_em_send_packets(int nb_rx, struct rte_mbuf **pk=
ts_burst,
> int32_t i, j;
> uint16_t dst_port[SENDM_PORT_OVERHEAD(MAX_PKT_BURST)];
>=20
> - if (nb_rx > 0) {
> - rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[0],
> + for (i =3D 0; i < prefetch_offset && i < nb_rx; i++)
> + rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i],
> struct rte_ether_hdr *) + 1);
> - }
>=20
> - for (i =3D 1, j =3D 0; j < nb_rx; i++, j++) {
> - if (i < nb_rx) {
> - rte_prefetch0(rte_pktmbuf_mtod(
> - pkts_burst[i],
> - struct rte_ether_hdr *) + 1);
> - }
> + for (j =3D 0; j < nb_rx - prefetch_offset; j++) {
> + rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[j + prefetch_offset],
> + struct rte_ether_hdr *) + 1);
> dst_port[j] =3D em_get_dst_port(qconf, pkts_burst[j], portid);
> }
>=20
> + for (; j < nb_rx; j++)
> + dst_port[j] =3D em_get_dst_port(qconf, pkts_burst[j], portid);
> +
> send_packets_multi(qconf, pkts_burst, dst_port, nb_rx);
> }
>=20
> @@ -106,20 +105,26 @@ static inline void
> l3fwd_em_process_events(int nb_rx, struct rte_event **events,
> struct lcore_conf *qconf)
> {
> + struct rte_mbuf *mbuf;
> + uint16_t port;
> int32_t i, j;
>=20
> - rte_prefetch0(rte_pktmbuf_mtod(events[0]->mbuf,
> - struct rte_ether_hdr *) + 1);
> + for (i =3D 0; i < prefetch_offset && i < nb_rx; i++)
> + rte_prefetch0(rte_pktmbuf_mtod(events[i]->mbuf, struct rte_ether_hdr *=
) + 1);
>=20
> - for (i =3D 1, j =3D 0; j < nb_rx; i++, j++) {
> - struct rte_mbuf *mbuf =3D events[j]->mbuf;
> - uint16_t port;
> + for (j =3D 0; j < nb_rx - prefetch_offset; j++) {
> + rte_prefetch0(rte_pktmbuf_mtod(events[j + prefetch_offset]->mbuf,
> + struct rte_ether_hdr *) + 1);
> + mbuf =3D events[j]->mbuf;
> + port =3D mbuf->port;
> + mbuf->port =3D em_get_dst_port(qconf, mbuf, mbuf->port);
> + process_packet(mbuf, &mbuf->port);
> + if (mbuf->port =3D=3D BAD_PORT)
> + mbuf->port =3D port;
> + }
>=20
> - if (i < nb_rx) {
> - rte_prefetch0(rte_pktmbuf_mtod(
> - events[i]->mbuf,
> - struct rte_ether_hdr *) + 1);
> - }
> + for (; j < nb_rx; j++) {
> + mbuf =3D events[j]->mbuf;
> port =3D mbuf->port;
> mbuf->port =3D em_get_dst_port(qconf, mbuf, mbuf->port);
> process_packet(mbuf, &mbuf->port);
> @@ -136,17 +141,22 @@ l3fwd_em_process_event_vector(struct rte_event_vect=
or *vec,
> struct rte_mbuf **mbufs =3D vec->mbufs;
> int32_t i, j;
>=20
> - rte_prefetch0(rte_pktmbuf_mtod(mbufs[0], struct rte_ether_hdr *) + 1);
> + for (i =3D 0; i < prefetch_offset && i < vec->nb_elem; i++)
> + rte_prefetch0(rte_pktmbuf_mtod(mbufs[i], struct rte_ether_hdr *) + 1);
>=20
> - for (i =3D 0, j =3D 1; i < vec->nb_elem; i++, j++) {
> - if (j < vec->nb_elem)
> - rte_prefetch0(rte_pktmbuf_mtod(mbufs[j],
> - struct rte_ether_hdr *) +
> - 1);
> + for (i =3D 0; i < vec->nb_elem - prefetch_offset; i++) {
> + rte_prefetch0(rte_pktmbuf_mtod(mbufs[i + prefetch_offset],
> + struct rte_ether_hdr *) + 1);
> dst_ports[i] =3D em_get_dst_port(qconf, mbufs[i],
> attr_valid ? vec->port :
> mbufs[i]->port);
> }
> +
> + for (; i < vec->nb_elem; i++)
> + dst_ports[i] =3D em_get_dst_port(qconf, mbufs[i],
> + attr_valid ? vec->port :
> + mbufs[i]->port);
> +
> j =3D RTE_ALIGN_FLOOR(vec->nb_elem, FWDSTEP);
>=20
> for (i =3D 0; i !=3D j; i +=3D FWDSTEP)
> diff --git a/examples/l3fwd/l3fwd_fib.c b/examples/l3fwd/l3fwd_fib.c
> index 82f1739df7..25192611c5 100644
> --- a/examples/l3fwd/l3fwd_fib.c
> +++ b/examples/l3fwd/l3fwd_fib.c
> @@ -24,9 +24,6 @@
> #include "l3fwd_event.h"
> #include "l3fwd_route.h"
>=20
> -/* Configure how many packets ahead to prefetch for fib. */
> -#define FIB_PREFETCH_OFFSET 4
> -
> /* A non-existent portid is needed to denote a default hop for fib. */
> #define FIB_DEFAULT_HOP 999
>=20
> @@ -130,14 +127,14 @@ fib_send_packets(int nb_rx, struct rte_mbuf **pkts_=
burst,
> int32_t i;
>=20
> /* Prefetch first packets. */
> - for (i =3D 0; i < FIB_PREFETCH_OFFSET && i < nb_rx; i++)
> + for (i =3D 0; i < prefetch_offset && i < nb_rx; i++)
> rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i], void *));
>=20
> /* Parse packet info and prefetch. */
> - for (i =3D 0; i < (nb_rx - FIB_PREFETCH_OFFSET); i++) {
> + for (i =3D 0; i < (nb_rx - prefetch_offset); i++) {
> /* Prefetch packet. */
> rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[
> - i + FIB_PREFETCH_OFFSET], void *));
> + i + prefetch_offset], void *));
> fib_parse_packet(pkts_burst[i],
> &ipv4_arr[ipv4_cnt], &ipv4_cnt,
> &ipv6_arr[ipv6_cnt], &ipv6_cnt,
> @@ -302,11 +299,11 @@ fib_event_loop(struct l3fwd_event_resources *evt_rs=
rc,
> ipv6_arr_assem =3D 0;
>=20
> /* Prefetch first packets. */
> - for (i =3D 0; i < FIB_PREFETCH_OFFSET && i < nb_deq; i++)
> + for (i =3D 0; i < prefetch_offset && i < nb_deq; i++)
> rte_prefetch0(rte_pktmbuf_mtod(events[i].mbuf, void *));
>=20
> /* Parse packet info and prefetch. */
> - for (i =3D 0; i < (nb_deq - FIB_PREFETCH_OFFSET); i++) {
> + for (i =3D 0; i < (nb_deq - prefetch_offset); i++) {
> if (flags & L3FWD_EVENT_TX_ENQ) {
> events[i].queue_id =3D tx_q_id;
> events[i].op =3D RTE_EVENT_OP_FORWARD;
> @@ -318,7 +315,7 @@ fib_event_loop(struct l3fwd_event_resources *evt_rsrc=
,
>=20
> /* Prefetch packet. */
> rte_prefetch0(rte_pktmbuf_mtod(events[
> - i + FIB_PREFETCH_OFFSET].mbuf,
> + i + prefetch_offset].mbuf,
> void *));
>=20
> fib_parse_packet(events[i].mbuf,
> @@ -455,12 +452,12 @@ fib_process_event_vector(struct rte_event_vector *v=
ec, uint8_t *type_arr,
> ipv6_arr_assem =3D 0;
>=20
> /* Prefetch first packets. */
> - for (i =3D 0; i < FIB_PREFETCH_OFFSET && i < vec->nb_elem; i++)
> + for (i =3D 0; i < prefetch_offset && i < vec->nb_elem; i++)
> rte_prefetch0(rte_pktmbuf_mtod(mbufs[i], void *));
>=20
> /* Parse packet info and prefetch. */
> - for (i =3D 0; i < (vec->nb_elem - FIB_PREFETCH_OFFSET); i++) {
> - rte_prefetch0(rte_pktmbuf_mtod(mbufs[i + FIB_PREFETCH_OFFSET],
> + for (i =3D 0; i < (vec->nb_elem - prefetch_offset); i++) {
> + rte_prefetch0(rte_pktmbuf_mtod(mbufs[i + prefetch_offset],
> void *));
> fib_parse_packet(mbufs[i], &ipv4_arr[ipv4_cnt], &ipv4_cnt,
> &ipv6_arr[ipv6_cnt], &ipv6_cnt, &type_arr[i]);
> diff --git a/examples/l3fwd/l3fwd_lpm.h b/examples/l3fwd/l3fwd_lpm.h
> index 4ee61e8d88..d81aa2efaf 100644
> --- a/examples/l3fwd/l3fwd_lpm.h
> +++ b/examples/l3fwd/l3fwd_lpm.h
> @@ -82,13 +82,13 @@ l3fwd_lpm_no_opt_send_packets(int nb_rx, struct rte_m=
buf **pkts_burst,
> int32_t j;
>=20
> /* Prefetch first packets */
> - for (j =3D 0; j < PREFETCH_OFFSET && j < nb_rx; j++)
> + for (j =3D 0; j < prefetch_offset && j < nb_rx; j++)
> rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[j], void *));
>=20
> /* Prefetch and forward already prefetched packets. */
> - for (j =3D 0; j < (nb_rx - PREFETCH_OFFSET); j++) {
> + for (j =3D 0; j < (nb_rx - prefetch_offset); j++) {
> rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[
> - j + PREFETCH_OFFSET], void *));
> + j + prefetch_offset], void *));
> l3fwd_lpm_simple_forward(pkts_burst[j], portid, qconf);
> }
>=20
> diff --git a/examples/l3fwd/l3fwd_lpm_neon.h b/examples/l3fwd/l3fwd_lpm_n=
eon.h
> index 3c1f827424..5570a11687 100644
> --- a/examples/l3fwd/l3fwd_lpm_neon.h
> +++ b/examples/l3fwd/l3fwd_lpm_neon.h
> @@ -85,23 +85,20 @@ l3fwd_lpm_process_packets(int nb_rx, struct rte_mbuf =
**pkts_burst,
> uint16_t portid, uint16_t *dst_port,
> struct lcore_conf *qconf, const uint8_t do_step3)
> {
> - int32_t i =3D 0, j =3D 0;
> + int32_t i =3D 0, j =3D 0, pos =3D 0;
> int32x4_t dip;
> uint32_t ipv4_flag;
> const int32_t k =3D RTE_ALIGN_FLOOR(nb_rx, FWDSTEP);
> const int32_t m =3D nb_rx % FWDSTEP;
>=20
> if (k) {
> - for (i =3D 0; i < FWDSTEP; i++) {
> - rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i],
> - void *));
> - }
> - for (j =3D 0; j !=3D k - FWDSTEP; j +=3D FWDSTEP) {
> - for (i =3D 0; i < FWDSTEP; i++) {
> - rte_prefetch0(rte_pktmbuf_mtod(
> - pkts_burst[j + i + FWDSTEP],
> - void *));
> - }
> + for (i =3D 0; i < prefetch_offset && i < k; i++)
> + rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i], void *));
> +
> + for (j =3D 0; j !=3D k; j +=3D FWDSTEP) {
> + for (i =3D 0, pos =3D j + prefetch_offset;
> + i < FWDSTEP && pos < k; i++, pos++)
> + rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[pos], void *));
>=20
> processx4_step1(&pkts_burst[j], &dip, &ipv4_flag);
> processx4_step2(qconf, dip, ipv4_flag, portid,
> @@ -109,35 +106,9 @@ l3fwd_lpm_process_packets(int nb_rx, struct rte_mbuf=
**pkts_burst,
> if (do_step3)
> processx4_step3(&pkts_burst[j], &dst_port[j]);
> }
> -
> - processx4_step1(&pkts_burst[j], &dip, &ipv4_flag);
> - processx4_step2(qconf, dip, ipv4_flag, portid, &pkts_burst[j],
> - &dst_port[j]);
> - if (do_step3)
> - processx4_step3(&pkts_burst[j], &dst_port[j]);
> -
> - j +=3D FWDSTEP;
> }
>=20
> if (m) {
> - /* Prefetch last up to 3 packets one by one */
> - switch (m) {
> - case 3:
> - rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[j],
> - void *));
> - j++;
> - /* fallthrough */
> - case 2:
> - rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[j],
> - void *));
> - j++;
> - /* fallthrough */
> - case 1:
> - rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[j],
> - void *));
> - j++;
> - }
> - j -=3D m;
> /* Classify last up to 3 packets one by one */
> switch (m) {
> case 3:
> diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
> index 994b7dd8e5..0920c0b2f6 100644
> --- a/examples/l3fwd/main.c
> +++ b/examples/l3fwd/main.c
> @@ -59,6 +59,7 @@ uint16_t nb_rxd =3D RX_DESC_DEFAULT;
> uint16_t nb_txd =3D TX_DESC_DEFAULT;
> uint32_t nb_pkt_per_burst =3D DEFAULT_PKT_BURST;
> uint32_t mb_mempool_cache_size =3D MEMPOOL_CACHE_SIZE;
> +uint16_t prefetch_offset =3D DEFAULT_PREFECH_OFFSET;
>=20
> /**< Ports set in promiscuous mode off by default. */
> static int promiscuous_on;
> @@ -769,6 +770,7 @@ static const char short_options[] =3D
> #define CMD_LINE_OPT_ALG "alg"
> #define CMD_LINE_OPT_PKT_BURST "burst"
> #define CMD_LINE_OPT_MB_CACHE_SIZE "mbcache"
> +#define CMD_PREFETCH_OFFSET "prefetch-offset"
>=20
> enum {
> /* long options mapped to a short option */
> @@ -800,6 +802,7 @@ enum {
> CMD_LINE_OPT_VECTOR_TMO_NS_NUM,
> CMD_LINE_OPT_PKT_BURST_NUM,
> CMD_LINE_OPT_MB_CACHE_SIZE_NUM,
> + CMD_PREFETCH_OFFSET_NUM,
> };
>=20
> static const struct option lgopts[] =3D {
> @@ -828,6 +831,7 @@ static const struct option lgopts[] =3D {
> {CMD_LINE_OPT_ALG, 1, 0, CMD_LINE_OPT_ALG_NUM},
> {CMD_LINE_OPT_PKT_BURST, 1, 0, CMD_LINE_OPT_PKT_BURST_NUM},
> {CMD_LINE_OPT_MB_CACHE_SIZE, 1, 0, CMD_LINE_OPT_MB_CACHE_SIZE_NUM},
> + {CMD_PREFETCH_OFFSET, 1, 0, CMD_PREFETCH_OFFSET_NUM},
> {NULL, 0, 0, 0}
> };
>=20
> @@ -1017,6 +1021,9 @@ parse_args(int argc, char **argv)
> case CMD_LINE_OPT_ALG_NUM:
> l3fwd_set_alg(optarg);
> break;
> + case CMD_PREFETCH_OFFSET_NUM:
> + prefetch_offset =3D strtol(optarg, NULL, 10);
Hmm... might be something like parse_max_pkt_len() is doing, to be more rob=
ust?
In fact, probably can re-use the same function, might be just name it in a =
more generic way.
=20
> + break;
> default:
> print_usage(prgname);
> return -1;
> @@ -1054,6 +1061,13 @@ parse_args(int argc, char **argv)
> }
> #endif
>=20
> + if (prefetch_offset > nb_pkt_per_burst) {
> + fprintf(stderr, "Prefetch offset (%u) cannot be greater than burst siz=
e (%u). "
> + "Using burst size %u.\n",
> + prefetch_offset, nb_pkt_per_burst, nb_pkt_per_burst);
> + prefetch_offset =3D nb_pkt_per_burst;
Might be just print err message and terminate gracefully?=20
> + }
> +
> /*
> * Nothing is selected, pick longest-prefix match
> * as default match.
> --
> 2.33.0