On Sunday 2009-08-23 11:02, Balazs Scheidler wrote:
>While looking for a place to add a new bitfield in ipv6_pinfo,
>I've found a 32 bit hole (in 64 bit mode) at the beginning of the struct.
>Since dst_cookie is used in the output fastpath, I've moved this field to
>fill the hole, thus decreasing the struct size on 64 bit platforms by
>4 bytes.
Hm? I do not see a size reduction. pahole(1) tells me [for a base of
v2.6.31-rc1-103-g644fc2c] the size is the same before and after.
--- p.1 2009-08-29 18:45:37.996787299 +0200
+++ p.2 2009-08-29 18:43:08.152753849 +0200
@@ -21824,10 +21824,8 @@ struct ipv6_pinfo {
struct in6_addr saddr; /* 0 16 */
struct in6_addr rcv_saddr; /* 16 16 */
struct in6_addr daddr; /* 32 16 */
- struct in6_pktinfo sticky_pktinfo; /* 48 20 */
-
- /* XXX 4 bytes hole, try to pack */
-
+ __u32 dst_cookie; /* 48 4 */
+ struct in6_pktinfo sticky_pktinfo; /* 52 20 */
/* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */
struct in6_addr * daddr_cache; /* 72 8 */
struct in6_addr * saddr_cache; /* 80 8 */
@@ -21862,7 +21860,9 @@ struct ipv6_pinfo {
__u8 ipv6only:1; /* 106: 3 1 */
__u8 srcprefs:3; /* 106: 0 1 */
__u8 tclass; /* 107 1 */
- __u32 dst_cookie; /* 108 4 */
+
+ /* XXX 4 bytes hole, try to pack */
+
struct ipv6_mc_socklist * ipv6_mc_list; /* 112 8 */
struct ipv6_ac_socklist * ipv6_ac_list; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
--
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