| Message ID | 1341978558.3265.6609.camel@edumazet-glaptop |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Wed, 2012-07-11 at 05:49 +0200, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.com> > > On 64 bit arches having efficient unaligned accesses (eg x86_64) we can > use long words to reduce number of instructions for free. Thanks Eric. This looks very sensible. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Wed, 11 Jul 2012 05:49:18 +0200 > From: Eric Dumazet <edumazet@google.com> > > On 64 bit arches having efficient unaligned accesses (eg x86_64) we can > use long words to reduce number of instructions for free. > > Signed-off-by: Eric Dumazet <edumazet@google.com> > Cc: Joe Perches <joe@perches.com> Maybe we can even be sure that they are 64-bit aligned too? If there's an embedded u64 in the in6_addr union, they really should be. It can't even be an issue in the protocol headers, because in the socket demux we read the two 32-bit ipv4 addresses in the packet header as one 64-bit chunk already. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2012-07-10 at 21:02 -0700, David Miller wrote: > From: Eric Dumazet <eric.dumazet@gmail.com> > Date: Wed, 11 Jul 2012 05:49:18 +0200 > > > From: Eric Dumazet <edumazet@google.com> > > > > On 64 bit arches having efficient unaligned accesses (eg x86_64) we can > > use long words to reduce number of instructions for free. > > > > Signed-off-by: Eric Dumazet <edumazet@google.com> > > Cc: Joe Perches <joe@perches.com> > > Maybe we can even be sure that they are 64-bit aligned too? > > If there's an embedded u64 in the in6_addr union, they really should > be. > > It can't even be an issue in the protocol headers, because in the > socket demux we read the two 32-bit ipv4 addresses in the packet > header as one 64-bit chunk already. I dont think this 8bytes alignment is possible with ip6tables. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Wed, 11 Jul 2012 06:07:58 +0200 > I dont think this 8bytes alignment is possible with ip6tables. Hmmm, wouldn't it make more sense to make ip6tables use a special accessor than to penalize everyone? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2012-07-11 at 05:49 +0200, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.com> > > On 64 bit arches having efficient unaligned accesses (eg x86_64) we can > use long words to reduce number of instructions for free. > > Signed-off-by: Eric Dumazet <edumazet@google.com> > Cc: Joe Perches <joe@perches.com> > --- > include/net/ipv6.h | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/include/net/ipv6.h b/include/net/ipv6.h > index aecf884..9ac5ded 100644 > --- a/include/net/ipv6.h > +++ b/include/net/ipv6.h > @@ -302,10 +302,19 @@ static inline int > ipv6_masked_addr_cmp(const struct in6_addr *a1, const struct in6_addr *m, > const struct in6_addr *a2) > { > +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 > + const unsigned long *ul1 = (const unsigned long *)a1; > + const unsigned long *ulm = (const unsigned long *)m; > + const unsigned long *ul2 = (const unsigned long *)a2; > + > + return !!(((ul1[0] ^ ul2[0]) & ulm[0]) | > + ((ul1[1] ^ ul2[1]) & ulm[1])); > +#else > return !!(((a1->s6_addr32[0] ^ a2->s6_addr32[0]) & m->s6_addr32[0]) | > ((a1->s6_addr32[1] ^ a2->s6_addr32[1]) & m->s6_addr32[1]) | > ((a1->s6_addr32[2] ^ a2->s6_addr32[2]) & m->s6_addr32[2]) | > ((a1->s6_addr32[3] ^ a2->s6_addr32[3]) & m->s6_addr32[3])); > +#endif > } Come to think of it, this should probably be bool to avoid anyone possibly using this in a sorting function. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2012-07-10 at 21:13 -0700, David Miller wrote: > From: Eric Dumazet <eric.dumazet@gmail.com> > Date: Wed, 11 Jul 2012 06:07:58 +0200 > > > I dont think this 8bytes alignment is possible with ip6tables. > > Hmmm, wouldn't it make more sense to make ip6tables use a special > accessor than to penalize everyone? But we cannot guarantee 64bit alignment everywhere. Think of tunnels for example. I dont see where in demux code we have a 64bit access ? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2012-07-11 at 06:44 +0200, Eric Dumazet wrote:
> I dont see where in demux code we have a 64bit access ?
I guess you meant the code in include/net/inet_hashtables.h ?
INET_ADDR_COOKIE() loads the two 32bits into one 64bit register/var
So there is no 64bit alignment in packet header itself.
Then, INET_MATCH does a *(u64 *)&(inet_sk(__sk)->inet_daddr)))
This happens to work because skc_daddr & skc_rcv_saddr are at the
beginning of struct sock_common, and its 8bytes aligned on 64bit arches.
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From: Eric Dumazet <eric.dumazet@gmail.com> Date: Wed, 11 Jul 2012 06:44:21 +0200 > I dont see where in demux code we have a 64bit access ? Oh I see, we only do it in the socket, sigh. #define INET_MATCH(__sk, __net, __hash, __cookie, __saddr, __daddr, __ports, __dif)\ (((__sk)->sk_hash == (__hash)) && net_eq(sock_net(__sk), (__net)) && \ ((*((__addrpair *)&(inet_sk(__sk)->inet_daddr))) == (__cookie)) && \ ((*((__portpair *)&(inet_sk(__sk)->inet_dport))) == (__ports)) && \ ... -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/net/ipv6.h b/include/net/ipv6.h index aecf884..9ac5ded 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -302,10 +302,19 @@ static inline int ipv6_masked_addr_cmp(const struct in6_addr *a1, const struct in6_addr *m, const struct in6_addr *a2) { +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 + const unsigned long *ul1 = (const unsigned long *)a1; + const unsigned long *ulm = (const unsigned long *)m; + const unsigned long *ul2 = (const unsigned long *)a2; + + return !!(((ul1[0] ^ ul2[0]) & ulm[0]) | + ((ul1[1] ^ ul2[1]) & ulm[1])); +#else return !!(((a1->s6_addr32[0] ^ a2->s6_addr32[0]) & m->s6_addr32[0]) | ((a1->s6_addr32[1] ^ a2->s6_addr32[1]) & m->s6_addr32[1]) | ((a1->s6_addr32[2] ^ a2->s6_addr32[2]) & m->s6_addr32[2]) | ((a1->s6_addr32[3] ^ a2->s6_addr32[3]) & m->s6_addr32[3])); +#endif } static inline void ipv6_addr_prefix(struct in6_addr *pfx, @@ -335,10 +344,17 @@ static inline void ipv6_addr_set(struct in6_addr *addr, static inline bool ipv6_addr_equal(const struct in6_addr *a1, const struct in6_addr *a2) { +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 + const unsigned long *ul1 = (const unsigned long *)a1; + const unsigned long *ul2 = (const unsigned long *)a2; + + return ((ul1[0] ^ ul2[0]) | (ul1[1] ^ ul2[1])) == 0UL; +#else return ((a1->s6_addr32[0] ^ a2->s6_addr32[0]) | (a1->s6_addr32[1] ^ a2->s6_addr32[1]) | (a1->s6_addr32[2] ^ a2->s6_addr32[2]) | (a1->s6_addr32[3] ^ a2->s6_addr32[3])) == 0; +#endif } static inline bool __ipv6_prefix_equal(const __be32 *a1, const __be32 *a2, @@ -391,8 +407,14 @@ bool ip6_frag_match(struct inet_frag_queue *q, void *a); static inline bool ipv6_addr_any(const struct in6_addr *a) { +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 + const unsigned long *ul = (const unsigned long *)a; + + return (ul[0] | ul[1]) == 0UL; +#else return (a->s6_addr32[0] | a->s6_addr32[1] | a->s6_addr32[2] | a->s6_addr32[3]) == 0; +#endif } static inline bool ipv6_addr_loopback(const struct in6_addr *a)