Date: Sun, 25 Feb 2007 15:21:08 +0100 From: Andre Oppermann <andre@freebsd.org> To: Kip Macy <kip.macy@gmail.com> Cc: freebsd-net <freebsd-net@freebsd.org> Subject: Re: improved TSO interface needed Message-ID: <45E19B54.9060007@freebsd.org> In-Reply-To: <b1fa29170702242255i323077e8t3e5cfe696431c50b@mail.gmail.com> References: <b1fa29170702242255i323077e8t3e5cfe696431c50b@mail.gmail.com>
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Kip Macy wrote:
> Evidently FreeBSD violates the LSO spec by sending down up to socket
> buffer sized TSO segments to the network card. Is there a way to set
> this other than reducing net.inet.tcp.sendbuf_max to a compliant value
> (64k)? And is there a way to for a device to communicate to the stack
> the maximum length of an mbuf chain?
From netinet/ip_output.c:
* When doing TSO limit a burst to TCP_MAXWIN minus the
* IP, TCP and Options length to keep ip->ip_len from
* overflowing. Prevent the last segment from being
* fractional thus making them all equal sized and set
* the flag to continue sending.
TCP_MAXWIN is 64K.
--
Andre
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