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Make m_megapullup() more intelligent:

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- to increase performance do not reallocate mbuf when possible,
 - to support up to 16K packets (was 2K max) use mbuf cluster of proper size.
This change depends on recent ng_nat and ip_fw_nat changes.
This commit is contained in:
Alexander Motin 2008-06-01 17:52:40 +00:00
parent a9a13b54e9
commit efc66711f9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=179478
1 changed files with 32 additions and 12 deletions
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44
sys/netinet/libalias/alias.c
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@ -1656,29 +1656,49 @@ LibAliasUnLoadAllModule(void)
* m_megapullup() - this function is a big hack.
* Thankfully, it's only used in ng_nat and ipfw+nat.
*
* It allocates an mbuf with cluster and copies the whole chain into cluster,
* so that it is all contiguous and the whole packet can be accessed via a
* plain (char *) pointer. This is required, because libalias doesn't know
* how to handle mbuf chains.
* It allocates an mbuf with cluster and copies the specified part of the chain
* into cluster, so that it is all contiguous and can be accessed via a plain
* (char *) pointer. This is required, because libalias doesn't know how to
* handle mbuf chains.
*
* On success, m_megapullup returns an mbuf with cluster containing the input
* packet, on failure NULL. In both cases, the input packet is consumed.
* On success, m_megapullup returns an mbuf (possibly with cluster) containing
* the input packet, on failure NULL. The input packet is always consumed.
*/
struct mbuf *
m_megapullup(struct mbuf *m, int len) {
struct mbuf *mcl;
caddr_t cp;
if (len > MCLBYTES)
if (len > m->m_pkthdr.len)
goto bad;
if ((mcl = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR)) == NULL)
/* Do not reallocate packet if it is sequentional,
* writable and has some extra space for expansion.
* XXX: Constant 100bytes is completely empirical. */
#define RESERVE 100
if (m->m_next == NULL && M_WRITABLE(m) && M_TRAILINGSPACE(m) >= RESERVE)
return (m);
if (len <= MCLBYTES - RESERVE) {
mcl = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
} else if (len < MJUM16BYTES) {
int size;
if (len <= MJUMPAGESIZE - RESERVE) {
size = MJUMPAGESIZE;
} else if (len <= MJUM9BYTES - RESERVE) {
size = MJUM9BYTES;
} else {
size = MJUM16BYTES;
};
mcl = m_getjcl(M_DONTWAIT, MT_DATA, M_PKTHDR, size);
} else {
goto bad;
}
if (mcl == NULL)
goto bad;
cp = mtod(mcl, caddr_t);
m_copydata(m, 0, len, cp);
m_move_pkthdr(mcl, m);
mcl->m_len = mcl->m_pkthdr.len;
m_copydata(m, 0, len, mtod(mcl, caddr_t));
mcl->m_len = mcl->m_pkthdr.len = len;
m_freem(m);
return (mcl);