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| author | Eric Dumazet <dada1@cosmosbay.com> | 2009-02-20 11:03:33 +0100 |
|---|---|---|
| committer | Patrick McHardy <kaber@trash.net> | 2009-02-20 11:03:33 +0100 |
| commit | 08361aa807ae5e5007cd226ca9e34287512de737 (patch) | |
| tree | 2b0a51af98e4df407f7bce90ca8cd1a065691b1c /net/ipv4 | |
| parent | 268cb38e1802db560c73167e643f14a3dcb4b07c (diff) | |
| download | linux-08361aa807ae5e5007cd226ca9e34287512de737.tar.gz linux-08361aa807ae5e5007cd226ca9e34287512de737.tar.bz2 linux-08361aa807ae5e5007cd226ca9e34287512de737.zip | |
netfilter: ip_tables: unfold two critical loops in ip_packet_match()
While doing oprofile tests I noticed two loops are not properly unrolled by gcc
Using a hand coded unrolled loop provides nice speedup : ipt_do_table
credited of 2.52 % of cpu instead of 3.29 % in tbench.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/netfilter/ip_tables.c | 33 |
1 files changed, 21 insertions, 12 deletions
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 08cde5bd70a5..e5294aec967d 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -74,6 +74,25 @@ do { \ Hence the start of any table is given by get_table() below. */ +static unsigned long ifname_compare(const char *_a, const char *_b, + const unsigned char *_mask) +{ + const unsigned long *a = (const unsigned long *)_a; + const unsigned long *b = (const unsigned long *)_b; + const unsigned long *mask = (const unsigned long *)_mask; + unsigned long ret; + + ret = (a[0] ^ b[0]) & mask[0]; + if (IFNAMSIZ > sizeof(unsigned long)) + ret |= (a[1] ^ b[1]) & mask[1]; + if (IFNAMSIZ > 2 * sizeof(unsigned long)) + ret |= (a[2] ^ b[2]) & mask[2]; + if (IFNAMSIZ > 3 * sizeof(unsigned long)) + ret |= (a[3] ^ b[3]) & mask[3]; + BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long)); + return ret; +} + /* Returns whether matches rule or not. */ /* Performance critical - called for every packet */ static inline bool @@ -83,7 +102,6 @@ ip_packet_match(const struct iphdr *ip, const struct ipt_ip *ipinfo, int isfrag) { - size_t i; unsigned long ret; #define FWINV(bool, invflg) ((bool) ^ !!(ipinfo->invflags & (invflg))) @@ -103,12 +121,7 @@ ip_packet_match(const struct iphdr *ip, return false; } - /* Look for ifname matches; this should unroll nicely. */ - for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) { - ret |= (((const unsigned long *)indev)[i] - ^ ((const unsigned long *)ipinfo->iniface)[i]) - & ((const unsigned long *)ipinfo->iniface_mask)[i]; - } + ret = ifname_compare(indev, ipinfo->iniface, ipinfo->iniface_mask); if (FWINV(ret != 0, IPT_INV_VIA_IN)) { dprintf("VIA in mismatch (%s vs %s).%s\n", @@ -117,11 +130,7 @@ ip_packet_match(const struct iphdr *ip, return false; } - for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) { - ret |= (((const unsigned long *)outdev)[i] - ^ ((const unsigned long *)ipinfo->outiface)[i]) - & ((const unsigned long *)ipinfo->outiface_mask)[i]; - } + ret = ifname_compare(outdev, ipinfo->outiface, ipinfo->outiface_mask); if (FWINV(ret != 0, IPT_INV_VIA_OUT)) { dprintf("VIA out mismatch (%s vs %s).%s\n", |