Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 08361aa8 authored by Eric Dumazet's avatar Eric Dumazet Committed by Patrick McHardy
Browse files

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: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent 268cb38e

net/ipv4/netfilter/ip_tables.c

+21 −12
Original line number Diff line number Diff line
@@ -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",