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SoftLRO for ixl(4), bnxt(4) and em(4)
From: Jan Klemkow <j.klemkow@wemelug.de>
Subject: Re: SoftLRO for ixl(4), bnxt(4) and em(4)
Date: Tue, 4 Mar 2025 20:02:31 +0100
> On Fri, Nov 15, 2024 at 11:30:08AM GMT, Jan Klemkow wrote:
>> On Thu, Nov 07, 2024 at 11:30:26AM GMT, David Gwynne wrote:
>> > On Thu, Nov 07, 2024 at 01:10:10AM +0100, Jan Klemkow wrote:
>> > > This diff introduces a software solution for TCP Large Receive Offload
>> > > (SoftLRO) for network interfaces don't hat hardware support for it.
>> > > This is needes at least for newer Intel interfaces as their
>> > > documentation said that LRO a.k.a. Receive Side Coalescing (RSC) has to
>> > > be done by software.
>> > > This diff coalesces TCP segments during the receive interrupt before
>> > > queueing them. Thus, our TCP/IP stack has to process less packet
>> > > headers per amount of received data.
>> > >
>> > > I measured receiving performance with Intel XXV710 25 GbE interfaces.
>> > > It increased from 6 Gbit/s to 23 Gbit/s.
>> > >
>> > > Even if we saturate em(4) without any of these technique its also part
>> > > this diff. I'm interested if this diff helps to reach 1 Gbit/s on old
>> > > or slow hardware.
>> > >
>> > > I also add bnxt(4) to this diff to increase test coverage. If you want
>> > > to tests this implementation with your favorite interface, just replace
>> > > the ml_enqueue() call with the new tcp_softlro_enqueue() (as seen
>> > > below). It should work with all kind network interfaces.
>> > >
>> > > Any comments and tests reports are welcome.
>> >
>> > nice.
>> >
>> > i would argue this should be ether_softlro_enqueue and put in
>> > if_ethersubr.c because it's specific to ethernet interfaces. we don't
>> > really have any other type of interface that bundles reception of
>> > packets that we can take advantage of like this, and internally it
>> > assumes it's pulling ethernet packets apart.
>> >
>> > aside from that, just a few comments on the code.
>>
>> I adapted your comments in the diff below.
>
> I refactored the SoftLRO diff. You just need to add the flags IFXF_LRO
> / IFCAP_LRO, and repalce ml_enqueue() with tcp_softlro_enqueue() to
> enable this on you favorit network device.
>
> Janne: I adjusted your diff with correct headers. But, I'm unable to
> test this part of the diff below, due to lack of hardware. Could you
> test it again?
>
> Yuichiro: Could you also retest your UDP/TCP forwarding test? I added a
> short path for non-TCP packets in the ixl(4) driver. Maybe its better
> now.
Thanks for your latest patch. It improves the ipgen test with 2 ixl(4) nics.
It looks very good performance shown as below.
```
rfc2544 tolerable error rate: 0.0000%
rfc2544 trial duration: 10 sec
rfc2544 pps resolution: 0.0000%
rfc2544 interval: 0 sec
rfc2544 warming duration: 1 sec
framesize|0G 1G 2G 3G 4G 5G 6G 7G 8G 9G 10Gbps
---------+----+----+----+----+----+----+----+----+----+----+
64 |#### 623.96Mbps, 1218672/14880952pps, 8.19%
128 |####### 1249.54Mbps, 1220252/ 8445945pps, 14.45%
512 |######################### 4813.20Mbps, 1175098/ 2349624pps, 50.01%
1024 |################################################# 9771.27Mbps, 1192782/ 1197318pps, 99.62%
1280 |################################################## 9845.54Mbps, 961479/ 961538pps, 99.99%
1408 |################################################## 9859.94Mbps, 875350/ 875350pps, 100.00%
1518 |################################################## 9869.91Mbps, 812740/ 812743pps, 100.00%
framesize|0 |1m |2m |3m |4m |5m |6m |7m |8m |9m |10m |11m |12m |13m |14m |15m pps
---------+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
64 |###### 1218672/14880952pps, 8.19%
128 |###### 1220252/ 8445945pps, 14.45%
512 |##### 1175098/ 2349624pps, 50.01%
1024 |##### 1192782/ 1197318pps, 99.62%
1280 |#### 961479/ 961538pps, 99.99%
1408 |#### 875350/ 875350pps, 100.00%
1518 |#### 812740/ 812743pps, 100.00%
```
However TCP forwarding performance looks the same as the first patch.
```
# iperf3 -c 192.168.200.10
Connecting to host 192.168.200.10, port 5201
[ 5] local 192.168.100.10 port 19800 connected to 192.168.200.10 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 343 MBytes 2.87 Gbits/sec 75 1.04 MBytes
[ 5] 1.00-2.00 sec 600 MBytes 5.03 Gbits/sec 0 1.61 MBytes
[ 5] 2.00-3.01 sec 582 MBytes 4.85 Gbits/sec 0 1.61 MBytes
[ 5] 3.01-4.01 sec 507 MBytes 4.26 Gbits/sec 0 1.61 MBytes
[ 5] 4.01-5.01 sec 420 MBytes 3.53 Gbits/sec 0 1.61 MBytes
[ 5] 5.01-6.01 sec 361 MBytes 3.03 Gbits/sec 0 1.61 MBytes
[ 5] 6.01-7.00 sec 349 MBytes 2.94 Gbits/sec 0 1.61 MBytes
[ 5] 7.00-8.00 sec 346 MBytes 2.91 Gbits/sec 0 1.61 MBytes
[ 5] 8.00-9.00 sec 354 MBytes 2.96 Gbits/sec 0 1.61 MBytes
[ 5] 9.00-10.00 sec 345 MBytes 2.90 Gbits/sec 0 1.61 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 4.11 GBytes 3.53 Gbits/sec 75 sender
[ 5] 0.00-10.00 sec 4.11 GBytes 3.53 Gbits/sec receiver
iperf Done.
# iperf3 -c 192.168.200.10 -R
Connecting to host 192.168.200.10, port 5201
Reverse mode, remote host 192.168.200.10 is sending
[ 5] local 192.168.100.10 port 10129 connected to 192.168.200.10 port 5201
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.01 sec 461 MBytes 3.84 Gbits/sec
[ 5] 1.01-2.00 sec 453 MBytes 3.83 Gbits/sec
[ 5] 2.00-3.00 sec 458 MBytes 3.83 Gbits/sec
[ 5] 3.00-4.00 sec 451 MBytes 3.79 Gbits/sec
[ 5] 4.00-5.00 sec 445 MBytes 3.74 Gbits/sec
[ 5] 5.00-6.06 sec 477 MBytes 3.77 Gbits/sec
[ 5] 6.06-7.00 sec 427 MBytes 3.81 Gbits/sec
[ 5] 7.00-8.00 sec 449 MBytes 3.78 Gbits/sec
[ 5] 8.00-9.04 sec 467 MBytes 3.78 Gbits/sec
[ 5] 9.04-10.00 sec 436 MBytes 3.80 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 4.42 GBytes 3.80 Gbits/sec 0 sender
[ 5] 0.00-10.00 sec 4.42 GBytes 3.80 Gbits/sec receiver
iperf Done.
```
I will look into more deeper what's happening on my OpenBSD kernel.
>
> Further tests and comments are welcome.
>
> Thanks,
> Jan
>
> Index: arch/octeon/dev/if_cnmac.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/octeon/dev/if_cnmac.c,v
> diff -u -p -r1.86 if_cnmac.c
> --- arch/octeon/dev/if_cnmac.c 20 May 2024 23:13:33 -0000 1.86
> +++ arch/octeon/dev/if_cnmac.c 4 Mar 2025 14:53:49 -0000
> @@ -55,6 +55,9 @@
> #include <net/if_media.h>
> #include <netinet/in.h>
> #include <netinet/if_ether.h>
> +#include <netinet/tcp.h>
> +#include <netinet/tcp_timer.h>
> +#include <netinet/tcp_var.h>
>
> #if NBPFILTER > 0
> #include <net/bpf.h>
> @@ -306,7 +309,7 @@ cnmac_attach(struct device *parent, stru
> strncpy(ifp->if_xname, sc->sc_dev.dv_xname, sizeof(ifp->if_xname));
> ifp->if_softc = sc;
> ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
> - ifp->if_xflags = IFXF_MPSAFE;
> + ifp->if_xflags = IFXF_MPSAFE | IFXF_LRO;
> ifp->if_ioctl = cnmac_ioctl;
> ifp->if_qstart = cnmac_start;
> ifp->if_watchdog = cnmac_watchdog;
> @@ -314,7 +317,7 @@ cnmac_attach(struct device *parent, stru
> ifq_init_maxlen(&ifp->if_snd, max(GATHER_QUEUE_SIZE, IFQ_MAXLEN));
>
> ifp->if_capabilities = IFCAP_VLAN_MTU | IFCAP_CSUM_TCPv4 |
> - IFCAP_CSUM_UDPv4 | IFCAP_CSUM_TCPv6 | IFCAP_CSUM_UDPv6;
> + IFCAP_CSUM_UDPv4 | IFCAP_CSUM_TCPv6 | IFCAP_CSUM_UDPv6 | IFCAP_LRO;
>
> cn30xxgmx_set_filter(sc->sc_gmx_port);
>
> @@ -1246,7 +1249,7 @@ cnmac_recv(struct cnmac_softc *sc, uint6
> M_TCP_CSUM_IN_OK | M_UDP_CSUM_IN_OK;
> }
>
> - ml_enqueue(ml, m);
> + tcp_softlro_enqueue(ifp, ml, m);
>
> return nmbuf;
>
> Index: dev/pci/if_bnxt.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/if_bnxt.c,v
> diff -u -p -r1.52 if_bnxt.c
> --- dev/pci/if_bnxt.c 6 Oct 2024 23:43:18 -0000 1.52
> +++ dev/pci/if_bnxt.c 4 Mar 2025 14:53:48 -0000
> @@ -646,6 +646,8 @@ bnxt_attach(struct device *parent, struc
> IFCAP_CSUM_UDPv4 | IFCAP_CSUM_TCPv4 | IFCAP_CSUM_UDPv6 |
> IFCAP_CSUM_TCPv6;
> ifp->if_capabilities |= IFCAP_TSOv4 | IFCAP_TSOv6;
> + ifp->if_xflags |= IFXF_LRO;
> + ifp->if_capabilities |= IFCAP_LRO;
> #if NVLAN > 0
> ifp->if_capabilities |= IFCAP_VLAN_HWTAGGING;
> #endif
> @@ -2283,6 +2285,7 @@ bnxt_rx(struct bnxt_softc *sc, struct bn
> struct bnxt_cp_ring *cpr, struct mbuf_list *ml, int *slots, int *agslots,
> struct cmpl_base *cmpl)
> {
> + struct ifnet *ifp = &sc->sc_ac.ac_if;
> struct mbuf *m, *am;
> struct bnxt_slot *bs;
> struct rx_pkt_cmpl *rxlo = (struct rx_pkt_cmpl *)cmpl;
> @@ -2355,7 +2358,7 @@ bnxt_rx(struct bnxt_softc *sc, struct bn
> (*agslots)++;
> }
>
> - ml_enqueue(ml, m);
> + tcp_softlro_enqueue(ifp, ml, m);
> return (0);
> }
>
> Index: dev/pci/if_em.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/if_em.c,v
> diff -u -p -r1.378 if_em.c
> --- dev/pci/if_em.c 31 Aug 2024 16:23:09 -0000 1.378
> +++ dev/pci/if_em.c 4 Mar 2025 14:53:48 -0000
> @@ -2013,6 +2013,9 @@ em_setup_interface(struct em_softc *sc)
> ifp->if_capabilities |= IFCAP_TSOv4 | IFCAP_TSOv6;
> }
>
> + ifp->if_xflags |= IFXF_LRO;
> + ifp->if_capabilities |= IFCAP_LRO;
> +
> /*
> * Specify the media types supported by this adapter and register
> * callbacks to update media and link information
> @@ -3185,7 +3188,8 @@ em_rxeof(struct em_queue *que)
> m->m_flags |= M_VLANTAG;
> }
> #endif
> - ml_enqueue(&ml, m);
> +
> + tcp_softlro_enqueue(ifp, &ml, m);
>
> que->rx.fmp = NULL;
> que->rx.lmp = NULL;
> Index: dev/pci/if_ixl.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/if_ixl.c,v
> diff -u -p -r1.102 if_ixl.c
> --- dev/pci/if_ixl.c 30 Oct 2024 18:02:45 -0000 1.102
> +++ dev/pci/if_ixl.c 4 Mar 2025 14:53:49 -0000
> @@ -883,6 +883,8 @@ struct ixl_rx_wb_desc_16 {
>
> #define IXL_RX_DESC_PTYPE_SHIFT 30
> #define IXL_RX_DESC_PTYPE_MASK (0xffULL << IXL_RX_DESC_PTYPE_SHIFT)
> +#define IXL_RX_DESC_PTYPE_MAC_IPV4_TCP 26
> +#define IXL_RX_DESC_PTYPE_MAC_IPV6_TCP 92
>
> #define IXL_RX_DESC_PLEN_SHIFT 38
> #define IXL_RX_DESC_PLEN_MASK (0x3fffULL << IXL_RX_DESC_PLEN_SHIFT)
> @@ -1976,6 +1978,9 @@ ixl_attach(struct device *parent, struct
> IFCAP_CSUM_TCPv6 | IFCAP_CSUM_UDPv6;
> ifp->if_capabilities |= IFCAP_TSOv4 | IFCAP_TSOv6;
>
> + ifp->if_xflags |= IFXF_LRO;
> + ifp->if_capabilities |= IFCAP_LRO;
> +
> ifmedia_init(&sc->sc_media, 0, ixl_media_change, ixl_media_status);
>
> ixl_media_add(sc, phy_types);
> @@ -3255,9 +3260,11 @@ ixl_rxeof(struct ixl_softc *sc, struct i
> struct ixl_rx_map *rxm;
> bus_dmamap_t map;
> unsigned int cons, prod;
> - struct mbuf_list ml = MBUF_LIST_INITIALIZER();
> + struct mbuf_list mlt = MBUF_LIST_INITIALIZER();
> + struct mbuf_list mlo = MBUF_LIST_INITIALIZER();
> struct mbuf *m;
> uint64_t word;
> + unsigned int ptype;
> unsigned int len;
> unsigned int mask;
> int done = 0;
> @@ -3294,6 +3301,8 @@ ixl_rxeof(struct ixl_softc *sc, struct i
> m = rxm->rxm_m;
> rxm->rxm_m = NULL;
>
> + ptype = (word & IXL_RX_DESC_PTYPE_MASK)
> + >> IXL_RX_DESC_PTYPE_SHIFT;
> len = (word & IXL_RX_DESC_PLEN_MASK) >> IXL_RX_DESC_PLEN_SHIFT;
> m->m_len = len;
> m->m_pkthdr.len = 0;
> @@ -3324,7 +3333,12 @@ ixl_rxeof(struct ixl_softc *sc, struct i
> #endif
>
> ixl_rx_checksum(m, word);
> - ml_enqueue(&ml, m);
> +
> + if (ptype == IXL_RX_DESC_PTYPE_MAC_IPV4_TCP ||
> + ptype == IXL_RX_DESC_PTYPE_MAC_IPV6_TCP)
> + tcp_softlro_enqueue(ifp, &mlt, m);
> + else
> + ml_enqueue(&mlo, m);
> } else {
> ifp->if_ierrors++; /* XXX */
> m_freem(m);
> @@ -3342,7 +3356,7 @@ ixl_rxeof(struct ixl_softc *sc, struct i
>
> if (done) {
> rxr->rxr_cons = cons;
> - if (ifiq_input(ifiq, &ml))
> + if (ifiq_input(ifiq, &mlt) || ifiq_input(ifiq, &mlo))
> if_rxr_livelocked(&rxr->rxr_acct);
> ixl_rxfill(sc, rxr);
> }
> Index: net/if.c
> ===================================================================
> RCS file: /cvs/src/sys/net/if.c,v
> diff -u -p -r1.728 if.c
> --- net/if.c 2 Mar 2025 21:28:31 -0000 1.728
> +++ net/if.c 4 Mar 2025 14:53:49 -0000
> @@ -3388,6 +3388,7 @@ ifsetlro(struct ifnet *ifp, int on)
> } else if (!on && ISSET(ifp->if_xflags, IFXF_LRO))
> CLR(ifp->if_xflags, IFXF_LRO);
>
> + error = 0;
> out:
> splx(s);
>
> Index: netinet/tcp_input.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/tcp_input.c,v
> diff -u -p -r1.433 tcp_input.c
> --- netinet/tcp_input.c 2 Mar 2025 21:28:32 -0000 1.433
> +++ netinet/tcp_input.c 4 Mar 2025 15:07:04 -0000
> @@ -84,6 +84,7 @@
> #include <net/if_var.h>
> #include <net/route.h>
>
> +#include <netinet/if_ether.h>
> #include <netinet/in.h>
> #include <netinet/ip.h>
> #include <netinet/in_pcb.h>
> @@ -4229,4 +4230,233 @@ syn_cache_respond(struct syn_cache *sc,
> }
> in_pcbunref(inp);
> return (error);
> +}
> +
> +int
> +tcp_softlro(struct mbuf *mhead, struct mbuf *mtail)
> +{
> + struct ether_extracted head;
> + struct ether_extracted tail;
> + struct mbuf *m;
> + unsigned int hdrlen;
> +
> + /*
> + * Check if head and tail are mergeable
> + */
> +
> + ether_extract_headers(mhead, &head);
> + ether_extract_headers(mtail, &tail);
> +
> + /* Don't merge packets of different VLANs */
> + if (head.evh && tail.evh) {
> + if (head.evh->evl_tag != tail.evh->evl_tag)
> + return 0;
> + } else if (head.evh || tail.evh)
> + return 0;
> +
> + /* Check IP header. */
> + if (head.ip4 && tail.ip4) {
> + /* Don't merge packets with invalid header checksum. */
> + if (!ISSET(mhead->m_pkthdr.csum_flags, M_IPV4_CSUM_IN_OK) ||
> + !ISSET(mtail->m_pkthdr.csum_flags, M_IPV4_CSUM_IN_OK))
> + return 0;
> +
> + /* Check IPv4 addresses. */
> + if (head.ip4->ip_src.s_addr != tail.ip4->ip_src.s_addr ||
> + head.ip4->ip_dst.s_addr != tail.ip4->ip_dst.s_addr)
> + return 0;
> +
> + /* Don't merge IPv4 fragments. */
> + if (ISSET(head.ip4->ip_off, htons(IP_OFFMASK | IP_MF)) ||
> + ISSET(tail.ip4->ip_off, htons(IP_OFFMASK | IP_MF)))
> + return 0;
> +
> + /* Check max. IPv4 length. */
> + if (head.iplen + tail.iplen > IP_MAXPACKET)
> + return 0;
> +
> + /* Don't merge IPv4 packets with option headers. */
> + if (head.iphlen != sizeof(struct ip) ||
> + tail.iphlen != sizeof(struct ip))
> + return 0;
> +
> + /* Don't non-TCP packets. */
> + if (head.ip4->ip_p != IPPROTO_TCP ||
> + tail.ip4->ip_p != IPPROTO_TCP)
> + return 0;
> + } else if (head.ip6 && tail.ip6) {
> + /* Check IPv6 addresses. */
> + if (!IN6_ARE_ADDR_EQUAL(&head.ip6->ip6_src, &tail.ip6->ip6_src) ||
> + !IN6_ARE_ADDR_EQUAL(&head.ip6->ip6_dst, &tail.ip6->ip6_dst))
> + return 0;
> +
> + /* Check max. IPv6 length. */
> + if ((head.iplen - head.iphlen) +
> + (tail.iplen - tail.iphlen) > IPV6_MAXPACKET)
> + return 0;
> +
> + /* Don't merge IPv6 packets with option headers nor non-TCP. */
> + if (head.ip6->ip6_nxt != IPPROTO_TCP ||
> + tail.ip6->ip6_nxt != IPPROTO_TCP)
> + return 0;
> + } else {
> + return 0;
> + }
> +
> + /* Check TCP header. */
> + if (!head.tcp || !tail.tcp)
> + return 0;
> +
> + /* Check TCP ports. */
> + if (head.tcp->th_sport != tail.tcp->th_sport ||
> + head.tcp->th_dport != tail.tcp->th_dport)
> + return 0;
> +
> + /* Don't merge empty segments. */
> + if (head.paylen == 0 || tail.paylen == 0)
> + return 0;
> +
> + /* Check for continues segments. */
> + if (ntohl(head.tcp->th_seq) + head.paylen != ntohl(tail.tcp->th_seq))
> + return 0;
> +
> + /* Just ACK and PUSH TCP flags are allowed. */
> + if (ISSET(head.tcp->th_flags, ~(TH_ACK|TH_PUSH)) ||
> + ISSET(tail.tcp->th_flags, ~(TH_ACK|TH_PUSH)))
> + return 0;
> +
> + /* TCP ACK flag has to be set. */
> + if (!ISSET(head.tcp->th_flags, TH_ACK) ||
> + !ISSET(tail.tcp->th_flags, TH_ACK))
> + return 0;
> +
> + /* Ignore segments with different TCP options. */
> + if (head.tcphlen - sizeof(struct tcphdr) !=
> + tail.tcphlen - sizeof(struct tcphdr))
> + return 0;
> +
> + /* Check for TCP options */
> + if (head.tcphlen > sizeof(struct tcphdr)) {
> + char *hopt = (char *)(head.tcp) + sizeof(struct tcphdr);
> + char *topt = (char *)(tail.tcp) + sizeof(struct tcphdr);
> + int optsize = head.tcphlen - sizeof(struct tcphdr);
> + int optlen;
> +
> + for (; optsize > 0; optsize -= optlen) {
> + /* Ignore segments with different TCP options. */
> + if (hopt[0] != topt[0] || hopt[1] != topt[1])
> + return 0;
> +
> + /* Get option length */
> + optlen = hopt[1];
> + if (hopt[0] == TCPOPT_NOP)
> + optlen = 1;
> + else if (optlen < 2 || optlen > optsize)
> + return 0; /* Illegal length */
> +
> + if (hopt[0] != TCPOPT_NOP &&
> + hopt[0] != TCPOPT_TIMESTAMP)
> + return 0; /* Unsupported TCP option */
> +
> + hopt += optlen;
> + topt += optlen;
> + }
> + }
> +
> + /*
> + * Prepare concatenation of head and tail.
> + */
> +
> + /* Adjust IP header. */
> + if (head.ip4) {
> + head.ip4->ip_len = htons(head.iplen + tail.paylen);
> + } else if (head.ip6) {
> + head.ip6->ip6_plen =
> + htons(head.iplen - head.iphlen + tail.paylen);
> + }
> +
> + /* Combine TCP flags from head and tail. */
> + if (ISSET(tail.tcp->th_flags, TH_PUSH))
> + SET(head.tcp->th_flags, TH_PUSH);
> +
> + /* Adjust TCP header. */
> + head.tcp->th_win = tail.tcp->th_win;
> + head.tcp->th_ack = tail.tcp->th_ack;
> +
> + /* Calculate header length of tail packet. */
> + hdrlen = sizeof(*tail.eh);
> + if (tail.evh)
> + hdrlen = sizeof(*tail.evh);
> + hdrlen += tail.iphlen;
> + hdrlen += tail.tcphlen;
> +
> + /* Skip protocol headers in tail. */
> + m_adj(mtail, hdrlen);
> + CLR(mtail->m_flags, M_PKTHDR);
> +
> + /* Concatenate */
> + for (m = mhead; m->m_next;)
> + m = m->m_next;
> + m->m_next = mtail;
> + mhead->m_pkthdr.len += tail.paylen;
> +
> + /* Flag mbuf as TSO packet with MSS. */
> + if (!ISSET(mhead->m_pkthdr.csum_flags, M_TCP_TSO)) {
> + /* Set CSUM_OUT flags in case of forwarding. */
> + SET(mhead->m_pkthdr.csum_flags, M_TCP_CSUM_OUT);
> + head.tcp->th_sum = 0;
> + if (head.ip4) {
> + SET(mhead->m_pkthdr.csum_flags, M_IPV4_CSUM_OUT);
> + head.ip4->ip_sum = 0;
> + }
> +
> + SET(mhead->m_pkthdr.csum_flags, M_TCP_TSO);
> + mhead->m_pkthdr.ph_mss = head.paylen;
> + tcpstat_inc(tcps_inhwlro);
> + tcpstat_inc(tcps_inpktlro); /* count head */
> + }
> + mhead->m_pkthdr.ph_mss = MAX(mhead->m_pkthdr.ph_mss, tail.paylen);
> + tcpstat_inc(tcps_inpktlro); /* count tail */
> +
> + return 1;
> +}
> +
> +void
> +tcp_softlro_enqueue(struct ifnet *ifp, struct mbuf_list *ml, struct mbuf *mtail)
> +{
> + struct mbuf *mhead;
> +
> + if (!ISSET(ifp->if_xflags, IFXF_LRO))
> + goto out;
> +
> + /* Don't merge packets with invalid header checksum. */
> + if (!ISSET(mtail->m_pkthdr.csum_flags, M_TCP_CSUM_IN_OK))
> + goto out;
> +
> + for (mhead = ml->ml_head; mhead != NULL; mhead = mhead->m_nextpkt) {
> + /* Don't merge packets with invalid header checksum. */
> + if (!ISSET(mhead->m_pkthdr.csum_flags, M_TCP_CSUM_IN_OK))
> + continue;
> +
> + /* Use RSS hash to skip packets of different connections. */
> + if (ISSET(mhead->m_pkthdr.csum_flags, M_FLOWID) &&
> + ISSET(mtail->m_pkthdr.csum_flags, M_FLOWID) &&
> + mhead->m_pkthdr.ph_flowid != mtail->m_pkthdr.ph_flowid)
> + continue;
> +
> + /* Don't merge packets of different VLANs */
> + if (ISSET(mhead->m_flags, M_VLANTAG) !=
> + ISSET(mtail->m_flags, M_VLANTAG))
> + continue;
> +
> + if (ISSET(mhead->m_flags, M_VLANTAG) &&
> + EVL_VLANOFTAG(mhead->m_pkthdr.ether_vtag) !=
> + EVL_VLANOFTAG(mtail->m_pkthdr.ether_vtag))
> + continue;
> +
> + if (tcp_softlro(mhead, mtail))
> + return;
> + }
> + out:
> + ml_enqueue(ml, mtail);
> }
> Index: netinet/tcp_var.h
> ===================================================================
> RCS file: /cvs/src/sys/netinet/tcp_var.h,v
> diff -u -p -r1.186 tcp_var.h
> --- netinet/tcp_var.h 2 Mar 2025 21:28:32 -0000 1.186
> +++ netinet/tcp_var.h 4 Mar 2025 14:53:48 -0000
> @@ -720,6 +720,7 @@ void tcp_init(void);
> int tcp_input(struct mbuf **, int *, int, int, struct netstack *);
> int tcp_mss(struct tcpcb *, int);
> void tcp_mss_update(struct tcpcb *);
> +void tcp_softlro_enqueue(struct ifnet *, struct mbuf_list *, struct mbuf *);
> u_int tcp_hdrsz(struct tcpcb *);
> void tcp_mtudisc(struct inpcb *, int);
> void tcp_mtudisc_increase(struct inpcb *, int);
--
Yuichiro NAITO (naito.yuichiro@gmail.com)
SoftLRO for ixl(4), bnxt(4) and em(4)