Date: Fri, 6 Nov 2015 20:41:49 +0000 From: "Cui, Cheng" <Cheng.Cui@netapp.com> To: "hselasky@FreeBSD.org" <hselasky@FreeBSD.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r271946 - in head/sys: dev/oce dev/vmware/vmxnet3 dev/xen/netfront kern net netinet ofed/drivers/net/mlx4 sys Message-ID: <FA688C89-5F93-4738-AB32-9EDBD8A9FD11@netapp.com>
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Hello Hans, This is Cheng Cui. I am reading the CURRENT FreeBSD code in tcp_output.c, a= nd find this question regarding your change in revision 271946. https://svnweb.freebsd.org/base/head/sys/netinet/tcp_output.c?r1=3D271946&r= 2=3D271945&pathrev=3D271946 trim data "len" under TSO: 885 /* 886 * Prevent the last segment from being 887 * fractional unless the send sockbuf can be 888 * emptied: 889 */ 890 max_len =3D (tp->t_maxopd - optlen); 891 if ((off + len) < sbavail(&so->so_snd)) { <= =3D=3D 892 moff =3D len % max_len; 893 if (moff !=3D 0) { 894 len -=3D moff; 895 sendalot =3D 1; 896 } 897 } Is there a specific reason that it should skip trimming the data "len" unde= r the condition of "(off + len) =3D=3D sbavail(&so->so_snd)" in TSO? Becaus= e I am wondering if we can trim the data "len" directly without checking th= e "(off + len)" condition. Thanks, --Cheng Cui NetApp Scale Out Networking
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