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Fix mbuf chain layout pessimization:

Browse Source 
in the case where a single mbuf is allocated due to
 m_getcl() returning NULL, we already call MH_ALIGN,
 so do not increment m->m_data in this case.

Found during MLDv2 port.
This commit is contained in:
Bruce M Simpson 2009-04-04 15:32:23 +00:00
parent 0fd99912de
commit 448895b7fc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=190692
1 changed files with 8 additions and 4 deletions
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12
sys/netinet/igmp.c
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@ -2784,8 +2784,11 @@ igmp_v3_enqueue_group_record(struct ifqueue *ifq, struct in_multi *inm,
m = NULL;
m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
sizeof(struct igmp_grouprec)) / sizeof(in_addr_t);
if (!is_state_change && !is_group_query)
if (!is_state_change && !is_group_query) {
m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
if (m)
m->m_data += IGMP_LEADINGSPACE;
}
if (m == NULL) {
m = m_gethdr(M_DONTWAIT, MT_DATA);
if (m)
@ -2793,7 +2796,6 @@ igmp_v3_enqueue_group_record(struct ifqueue *ifq, struct in_multi *inm,
}
if (m == NULL)
return (-ENOMEM);
m->m_data += IGMP_LEADINGSPACE;
igmp_save_context(m, ifp);
@ -2909,6 +2911,8 @@ igmp_v3_enqueue_group_record(struct ifqueue *ifq, struct in_multi *inm,
return (-ENOMEM);
}
m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
if (m)
m->m_data += IGMP_LEADINGSPACE;
if (m == NULL) {
m = m_gethdr(M_DONTWAIT, MT_DATA);
if (m)
@ -2917,7 +2921,6 @@ igmp_v3_enqueue_group_record(struct ifqueue *ifq, struct in_multi *inm,
if (m == NULL)
return (-ENOMEM);
igmp_save_context(m, ifp);
m->m_data += IGMP_LEADINGSPACE;
md = m_getptr(m, 0, &off);
pig = (struct igmp_grouprec *)(mtod(md, uint8_t *) + off);
CTR1(KTR_IGMPV3, "%s: allocated next packet", __func__);
@ -3063,6 +3066,8 @@ igmp_v3_enqueue_filter_change(struct ifqueue *ifq, struct in_multi *inm)
"%s: use previous packet", __func__);
} else {
m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
if (m)
m->m_data += IGMP_LEADINGSPACE;
if (m == NULL) {
m = m_gethdr(M_DONTWAIT, MT_DATA);
if (m)
@ -3075,7 +3080,6 @@ igmp_v3_enqueue_filter_change(struct ifqueue *ifq, struct in_multi *inm)
}
m->m_pkthdr.PH_vt.vt_nrecs = 0;
igmp_save_context(m, ifp);
m->m_data += IGMP_LEADINGSPACE;
m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
sizeof(struct igmp_grouprec)) /
sizeof(in_addr_t);