* [PATCH 1/2] net: ipv4: route.c: add likely() statements
@ 2021-03-24 3:09 Yejune Deng
2021-03-24 10:34 ` Leon Romanovsky
0 siblings, 1 reply; 4+ messages in thread
From: Yejune Deng @ 2021-03-24 3:09 UTC (permalink / raw)
To: davem, yoshfuji, dsahern, kuba; +Cc: netdev, linux-kernel, yejune, Yejune Deng
Add likely() statements in ipv4_confirm_neigh() for 'rt->rt_gw_family
== AF_INET'.
Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
---
net/ipv4/route.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index fa68c2612252..5762d9bc671c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -440,7 +440,7 @@ static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
struct net_device *dev = dst->dev;
const __be32 *pkey = daddr;
- if (rt->rt_gw_family == AF_INET) {
+ if (likely(rt->rt_gw_family == AF_INET)) {
pkey = (const __be32 *)&rt->rt_gw4;
} else if (rt->rt_gw_family == AF_INET6) {
return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
--
2.29.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] net: ipv4: route.c: add likely() statements
2021-03-24 3:09 [PATCH 1/2] net: ipv4: route.c: add likely() statements Yejune Deng
@ 2021-03-24 10:34 ` Leon Romanovsky
2021-03-24 11:01 ` Yejune Deng
0 siblings, 1 reply; 4+ messages in thread
From: Leon Romanovsky @ 2021-03-24 10:34 UTC (permalink / raw)
To: Yejune Deng; +Cc: davem, yoshfuji, dsahern, kuba, netdev, linux-kernel, yejune
On Wed, Mar 24, 2021 at 11:09:22AM +0800, Yejune Deng wrote:
> Add likely() statements in ipv4_confirm_neigh() for 'rt->rt_gw_family
> == AF_INET'.
Why? Such macros are beneficial in only specific cases, most of the time,
likely/unlikely is cargo cult.
>
> Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
> ---
> net/ipv4/route.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index fa68c2612252..5762d9bc671c 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -440,7 +440,7 @@ static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
> struct net_device *dev = dst->dev;
> const __be32 *pkey = daddr;
>
> - if (rt->rt_gw_family == AF_INET) {
> + if (likely(rt->rt_gw_family == AF_INET)) {
> pkey = (const __be32 *)&rt->rt_gw4;
> } else if (rt->rt_gw_family == AF_INET6) {
> return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
> --
> 2.29.0
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] net: ipv4: route.c: add likely() statements
2021-03-24 10:34 ` Leon Romanovsky
@ 2021-03-24 11:01 ` Yejune Deng
2021-03-24 12:19 ` Leon Romanovsky
0 siblings, 1 reply; 4+ messages in thread
From: Yejune Deng @ 2021-03-24 11:01 UTC (permalink / raw)
To: Leon Romanovsky
Cc: David Miller, yoshfuji, dsahern, Jakub Kicinski, netdev,
Linux Kernel Mailing List, yejune
My reasons are as following: ipv4_confirm_neigh() belongs to
ipv4_dst_ops that family is AF_INET, and ipv4_neigh_lookup() is also
added likely() when rt->rt_gw_family is equal to AF_INET.
On Wed, Mar 24, 2021 at 6:34 PM Leon Romanovsky <leon@kernel.org> wrote:
>
> On Wed, Mar 24, 2021 at 11:09:22AM +0800, Yejune Deng wrote:
> > Add likely() statements in ipv4_confirm_neigh() for 'rt->rt_gw_family
> > == AF_INET'.
>
> Why? Such macros are beneficial in only specific cases, most of the time,
> likely/unlikely is cargo cult.
>
> >
> > Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
> > ---
> > net/ipv4/route.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> > index fa68c2612252..5762d9bc671c 100644
> > --- a/net/ipv4/route.c
> > +++ b/net/ipv4/route.c
> > @@ -440,7 +440,7 @@ static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
> > struct net_device *dev = dst->dev;
> > const __be32 *pkey = daddr;
> >
> > - if (rt->rt_gw_family == AF_INET) {
> > + if (likely(rt->rt_gw_family == AF_INET)) {
> > pkey = (const __be32 *)&rt->rt_gw4;
> > } else if (rt->rt_gw_family == AF_INET6) {
> > return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
> > --
> > 2.29.0
> >
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] net: ipv4: route.c: add likely() statements
2021-03-24 11:01 ` Yejune Deng
@ 2021-03-24 12:19 ` Leon Romanovsky
0 siblings, 0 replies; 4+ messages in thread
From: Leon Romanovsky @ 2021-03-24 12:19 UTC (permalink / raw)
To: Yejune Deng
Cc: David Miller, yoshfuji, dsahern, Jakub Kicinski, netdev,
Linux Kernel Mailing List, yejune
On Wed, Mar 24, 2021 at 07:01:19PM +0800, Yejune Deng wrote:
> My reasons are as following: ipv4_confirm_neigh() belongs to
> ipv4_dst_ops that family is AF_INET, and ipv4_neigh_lookup() is also
> added likely() when rt->rt_gw_family is equal to AF_INET.
It is part of that cargo cult. Please support your claim with
performance numbers when this likely/unlikely will give any difference.
Thanks
>
> On Wed, Mar 24, 2021 at 6:34 PM Leon Romanovsky <leon@kernel.org> wrote:
> >
> > On Wed, Mar 24, 2021 at 11:09:22AM +0800, Yejune Deng wrote:
> > > Add likely() statements in ipv4_confirm_neigh() for 'rt->rt_gw_family
> > > == AF_INET'.
> >
> > Why? Such macros are beneficial in only specific cases, most of the time,
> > likely/unlikely is cargo cult.
> >
> > >
> > > Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
> > > ---
> > > net/ipv4/route.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> > > index fa68c2612252..5762d9bc671c 100644
> > > --- a/net/ipv4/route.c
> > > +++ b/net/ipv4/route.c
> > > @@ -440,7 +440,7 @@ static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
> > > struct net_device *dev = dst->dev;
> > > const __be32 *pkey = daddr;
> > >
> > > - if (rt->rt_gw_family == AF_INET) {
> > > + if (likely(rt->rt_gw_family == AF_INET)) {
> > > pkey = (const __be32 *)&rt->rt_gw4;
> > > } else if (rt->rt_gw_family == AF_INET6) {
> > > return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
> > > --
> > > 2.29.0
> > >
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-03-24 12:20 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-03-24 3:09 [PATCH 1/2] net: ipv4: route.c: add likely() statements Yejune Deng
2021-03-24 10:34 ` Leon Romanovsky
2021-03-24 11:01 ` Yejune Deng
2021-03-24 12:19 ` Leon Romanovsky
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