[src/trunk]: src/sys/netinet when doing TSO, avoid to use duplicated ip_id he...

[yamt <yamt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e7c162ed4db9
branches:  trunk
changeset: 580060:e7c162ed4db9
user:      yamt <yamt%NetBSD.org@localhost>
date:      Thu Apr 07 12:22:47 2005 +0000

description:
when doing TSO, avoid to use duplicated ip_id heavily.
XXX ip_randomid

diffstat:

 sys/netinet/ip_output.c |  25 ++++++++++++++++++++++---
 sys/netinet/ip_var.h    |  28 ++++++++++++++++++++++++----
 2 files changed, 46 insertions(+), 7 deletions(-)

diffs (92 lines):

diff -r 1ec0459cb8e9 -r e7c162ed4db9 sys/netinet/ip_output.c
--- a/sys/netinet/ip_output.c   Thu Apr 07 12:12:51 2005 +0000
+++ b/sys/netinet/ip_output.c   Thu Apr 07 12:22:47 2005 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ip_output.c,v 1.149 2005/03/11 17:07:51 matt Exp $     */
+/*     $NetBSD: ip_output.c,v 1.150 2005/04/07 12:22:47 yamt Exp $     */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -98,7 +98,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ip_output.c,v 1.149 2005/03/11 17:07:51 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ip_output.c,v 1.150 2005/04/07 12:22:47 yamt Exp $");
 
 #include "opt_pfil_hooks.h"
 #include "opt_inet.h"
@@ -235,7 +235,26 @@
        if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
                ip->ip_v = IPVERSION;
                ip->ip_off = htons(0);
-               ip->ip_id = ip_newid();
+               if ((m->m_pkthdr.csum_flags & M_CSUM_TSOv4) == 0) {
+                       ip->ip_id = ip_newid();
+               } else {
+
+                       /*
+                        * TSO capable interfaces (typically?) increment
+                        * ip_id for each segment.
+                        * "allocate" enough ids here to increase the chance
+                        * for them to be unique.
+                        *
+                        * note that the following calculation is not
+                        * needed to be precise.  wasting some ip_id is fine.
+                        */
+
+                       unsigned int segsz = m->m_pkthdr.segsz;
+                       unsigned int datasz = ntohs(ip->ip_len) - hlen;
+                       unsigned int num = howmany(datasz, segsz);
+
+                       ip->ip_id = ip_newid_range(num);
+               }
                ip->ip_hl = hlen >> 2;
                ipstat.ips_localout++;
        } else {
diff -r 1ec0459cb8e9 -r e7c162ed4db9 sys/netinet/ip_var.h
--- a/sys/netinet/ip_var.h      Thu Apr 07 12:12:51 2005 +0000
+++ b/sys/netinet/ip_var.h      Thu Apr 07 12:22:47 2005 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ip_var.h,v 1.69 2004/12/15 04:25:19 thorpej Exp $      */
+/*     $NetBSD: ip_var.h,v 1.70 2005/04/07 12:22:47 yamt Exp $ */
 
 /*
  * Copyright (c) 1982, 1986, 1993
@@ -263,13 +263,33 @@
 u_int16_t ip_randomid(void);
 extern int ip_do_randomid;
 
+/*
+ * ip_newid_range: "allocate" num contiguous ip_ids.
+ *
+ * => return the first id.
+ */
+
+static __inline uint16_t
+ip_newid_range(unsigned int num)
+{
+       uint16_t id;
+
+       if (ip_do_randomid) {
+               /* XXX ignore num */
+               return ip_randomid();
+       }
+
+       id = htons(ip_id);
+       ip_id += num;
+
+       return id;
+}
+
 static __inline uint16_t
 ip_newid(void)
 {
-       if (ip_do_randomid)
-               return ip_randomid();
 
-       return htons(ip_id++);
+       return ip_newid_range(1);
 }
 
 #endif  /* _KERNEL */