| Message ID | 20140923085437.696B81AB26D@localhost.localdomain |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Tue, 2014-09-23 at 10:54 +0200, Christophe Leroy wrote: > csum_partial() is a generic function which is not optimised for small fixed > length calculations, and its use requires to store "from" and "to" values in > memory while we already have them available in registers. This also has impact, > especially on RISC processors. In the same spirit as the change done by > Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4() > taking into account RFC1624. > > I spotted during a NATted tcp transfert that csum_partial() is one of top 5 > consuming functions (around 8%), and the second user of csum_partial() is > inet_proto_csum_replace4(). > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> > Acked-by: Eric Dumazet <edumazet@google.com> Thanks ! -- 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: Christophe Leroy <christophe.leroy@c-s.fr> Date: Tue, 23 Sep 2014 10:54:37 +0200 (CEST) > csum_partial() is a generic function which is not optimised for small fixed > length calculations, and its use requires to store "from" and "to" values in > memory while we already have them available in registers. This also has impact, > especially on RISC processors. In the same spirit as the change done by > Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4() > taking into account RFC1624. > > I spotted during a NATted tcp transfert that csum_partial() is one of top 5 > consuming functions (around 8%), and the second user of csum_partial() is > inet_proto_csum_replace4(). > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Also applied, thanks Christophe. -- 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/net/core/utils.c b/net/core/utils.c index eed3433..efc76dd 100644 --- a/net/core/utils.c +++ b/net/core/utils.c @@ -306,16 +306,14 @@ EXPORT_SYMBOL(in6_pton); void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, __be32 from, __be32 to, int pseudohdr) { - __be32 diff[] = { ~from, to }; if (skb->ip_summed != CHECKSUM_PARTIAL) { - *sum = csum_fold(csum_partial(diff, sizeof(diff), - ~csum_unfold(*sum))); + *sum = csum_fold(csum_add(csum_sub(~csum_unfold(*sum), from), + to)); if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr) - skb->csum = ~csum_partial(diff, sizeof(diff), - ~skb->csum); + skb->csum = ~csum_add(csum_sub(~(skb->csum), from), to); } else if (pseudohdr) - *sum = ~csum_fold(csum_partial(diff, sizeof(diff), - csum_unfold(*sum))); + *sum = ~csum_fold(csum_add(csum_sub(csum_unfold(*sum), from), + to)); } EXPORT_SYMBOL(inet_proto_csum_replace4);
csum_partial() is a generic function which is not optimised for small fixed length calculations, and its use requires to store "from" and "to" values in memory while we already have them available in registers. This also has impact, especially on RISC processors. In the same spirit as the change done by Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4() taking into account RFC1624. I spotted during a NATted tcp transfert that csum_partial() is one of top 5 consuming functions (around 8%), and the second user of csum_partial() is inet_proto_csum_replace4(). Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- -- net/core/utils.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)