From: Jan Klemkow <jan@openbsd.org>
Subject: Re: names for TSO and LRO
To: Alexander Bluhm <bluhm@openbsd.org>
Cc: tech@openbsd.org
Date: Thu, 17 Apr 2025 15:23:43 +0200

On Wed, Apr 16, 2025 at 11:39:21PM +0200, Alexander Bluhm wrote:
> Also the netstat -s description is not quite right anymore.  The
> idea is that we have one counter each when we do something in
> software, and one for offloading.  The loopback pseudo device it
> special, as it just passes large packets.
> 
> Here is an expample for lo(4).  Large packets are processed by
> device, but no small packets are on the network.
> 
> tcp:
>         34977 packets sent
>                 0 output TSO large packets chopped in software
>                 1486 output TSO large packets to device
>                 0 output TSO generated packets sent to network
>                 0 bad TSO packets dropped
>         34970 packets received
>                 0 input LRO generated packets glued in software
>                 1486 input LRO generated packets from device
>                 0 input LRO small packets received from network
>                 0 bad LRO packets dropped
> 
> And this is accounted with ixl(4).  TSO is done in hardware, LRO
> is software only implementation.
> 
> tcp:
>         3267132 packets sent
>                 0 output TSO large packets chopped in software
>                 4644123 output TSO large packets to device
>                 57013318 output TSO generated packets sent to network
>                 0 bad TSO packets dropped
>         5962903 packets received
>                 5663423 input LRO generated packets glued in software
>                 0 input LRO generated packets from device
>                 40208598 input LRO small packets received from network
>                 0 bad LRO packets dropped
> 
> ok?

I like this rephrasing of the counter descriptions.
As well as the fix of the loopback counter.

ok jan@ for the part below

Thanks,
Jan

> Index: sys/net/if.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/if.c,v
> diff -u -p -r1.729 if.c
> --- sys/net/if.c	19 Mar 2025 23:29:49 -0000	1.729
> +++ sys/net/if.c	16 Apr 2025 20:39:52 -0000
> @@ -824,9 +824,7 @@ if_input_local(struct ifnet *ifp, struct
>  		    ISSET(ifp->if_capabilities, IFCAP_TSOv4)) ||
>  		    (af == AF_INET6 &&
>  		    ISSET(ifp->if_capabilities, IFCAP_TSOv6)))) {
> -			tcpstat_inc(tcps_inswlro);
> -			tcpstat_add(tcps_inpktlro,
> -			    (m->m_pkthdr.len + ifp->if_mtu - 1) / ifp->if_mtu);
> +			tcpstat_inc(tcps_inhwlro);
>  		} else {
>  			tcpstat_inc(tcps_inbadlro);
>  			m_freem(m);
> Index: usr.bin/netstat/inet.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/usr.bin/netstat/inet.c,v
> diff -u -p -r1.183 inet.c
> --- usr.bin/netstat/inet.c	12 Aug 2024 06:22:36 -0000	1.183
> +++ usr.bin/netstat/inet.c	16 Apr 2025 21:18:39 -0000
> @@ -408,10 +408,13 @@ tcp_stats(char *name)
>  	p(tcps_sndwinup, "\t\t%u window update packet%s\n");
>  	p(tcps_sndctrl, "\t\t%u control packet%s\n");
>  	p(tcps_outswcsum, "\t\t%u packet%s software-checksummed\n");
> -	p(tcps_outswtso, "\t\t%u output TSO packet%s software chopped\n");
> -	p(tcps_outhwtso, "\t\t%u output TSO packet%s hardware processed\n");
> -	p(tcps_outpkttso, "\t\t%u output TSO packet%s generated\n");
> -	p(tcps_outbadtso, "\t\t%u output TSO packet%s dropped\n");
> +	p(tcps_outswtso,
> +	    "\t\t%u output TSO large packet%s chopped in software\n");
> +	p(tcps_outhwtso,
> +	    "\t\t%u output TSO large packet%s to device\n");
> +	p(tcps_outpkttso,
> +	    "\t\t%u output TSO generated packet%s sent to network\n");
> +	p(tcps_outbadtso, "\t\t%u bad TSO packet%s dropped\n");
>  	p(tcps_rcvtotal, "\t%u packet%s received\n");
>  	p2(tcps_rcvackpack, tcps_rcvackbyte, "\t\t%u ack%s (for %llu byte%s)\n");
>  	p(tcps_rcvdupack, "\t\t%u duplicate ack%s\n");
> @@ -440,11 +443,12 @@ tcp_stats(char *name)
>  	p(tcps_rcvbadsig, "\t\t%u bad/missing md5 checksum%s\n");
>  	p(tcps_rcvgoodsig, "\t\t%llu good md5 checksum%s\n");
>  	p(tcps_inswlro,
> -	    "\t\t%u input LRO packet%s passed through pseudo device\n");
> -	p(tcps_inhwlro, "\t\t%u input LRO generated packet%s from hardware\n");
> +	    "\t\t%u input LRO generated packet%s glued in software\n");
> +	p(tcps_inhwlro,
> +	    "\t\t%u input LRO generated packet%s from device\n");
>  	p(tcps_inpktlro,
> -	    "\t\t%u input LRO coalesced packet%s by network device\n");
> -	p(tcps_inbadlro, "\t\t%u input bad LRO packet%s dropped\n");
> +	    "\t\t%u input LRO small packet%s received from network\n");
> +	p(tcps_inbadlro, "\t\t%u bad LRO packet%s dropped\n");
>  	p(tcps_connattempt, "\t%u connection request%s\n");
>  	p(tcps_accepts, "\t%u connection accept%s\n");
>  	p(tcps_connects, "\t%u connection%s established (including accepts)\n");