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From: Robert Watson <rwatson@FreeBSD.org>
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To: Kip Macy <kmacy@FreeBSD.org>
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Cc: src-committers@freebsd.org, svn-src-user@freebsd.org
Subject: Re: svn commit: r193698 - user/kmacy/releng_7_2_fcs/sys/netinet
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On Mon, 8 Jun 2009, Kip Macy wrote:

>  skip idiv if queue is empty

A more general optimization might be to check whether ip->ip_len is > mtu 
before doing the idiv case...

Robert N M Watson
Computer Laboratory
University of Cambridge

>
> Modified:
>  user/kmacy/releng_7_2_fcs/sys/netinet/ip_output.c
>
> Modified: user/kmacy/releng_7_2_fcs/sys/netinet/ip_output.c
> ==============================================================================
> --- user/kmacy/releng_7_2_fcs/sys/netinet/ip_output.c	Mon Jun  8 09:13:16 2009	(r193697)
> +++ user/kmacy/releng_7_2_fcs/sys/netinet/ip_output.c	Mon Jun  8 09:19:25 2009	(r193698)
> @@ -447,12 +447,14 @@ again:
> 	 * interface in which case packetdrop should be done by queueing.
> 	 */
> #ifdef ALTQ
> -	if ((!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
> +	if (ifp->if_snd.ifq_len &&
> +	    (!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
> 	    ((ifp->if_snd.ifq_len + ip->ip_len / mtu + 1) >=
> 	    ifp->if_snd.ifq_maxlen))
> #else
> -	if ((ifp->if_snd.ifq_len + ip->ip_len / mtu + 1) >=
> -	    ifp->if_snd.ifq_maxlen)
> +	if (ifp->if_snd.ifq_len &&
> +	    ((ifp->if_snd.ifq_len + ip->ip_len / mtu + 1) >=
> +		ifp->if_snd.ifq_maxlen))
> #endif /* ALTQ */
> 	{
> 		error = ENOBUFS;
>