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| author | Breno Leitao <leitao@debian.org> | 2024-10-08 09:32:04 -0700 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2024-10-10 11:57:34 +0200 |
| commit | 9e542ff8b79ae1871074d3a7dca7de9e7374eeda (patch) | |
| tree | 956f9480806e1e6558470152cf6fc9f7d27f1865 | |
| parent | Merge branch 'ipv4-namespacify-ipv4-address-hash-table' (diff) | |
| download | linux-9e542ff8b79ae1871074d3a7dca7de9e7374eeda.tar.gz linux-9e542ff8b79ae1871074d3a7dca7de9e7374eeda.zip | |
net: Remove likely from l3mdev_master_ifindex_by_index
The likely() annotation in l3mdev_master_ifindex_by_index() has been
found to be incorrect 100% of the time in real-world workloads (e.g.,
web servers).
Annotated branches shows the following in these servers:
correct incorrect % Function File Line
0 169053813 100 l3mdev_master_ifindex_by_index l3mdev.h 81
This is happening because l3mdev_master_ifindex_by_index() is called
from __inet_check_established(), which calls
l3mdev_master_ifindex_by_index() passing the socked bounded interface.
l3mdev_master_ifindex_by_index(net, sk->sk_bound_dev_if);
Since most sockets are not going to be bound to a network device,
the likely() is giving the wrong assumption.
Remove the likely() annotation to ensure more accurate branch
prediction.
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241008163205.3939629-1-leitao@debian.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | include/net/l3mdev.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h index 031c661aa14d..2d6141f28b53 100644 --- a/include/net/l3mdev.h +++ b/include/net/l3mdev.h @@ -78,7 +78,7 @@ static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex) struct net_device *dev; int rc = 0; - if (likely(ifindex)) { + if (ifindex) { rcu_read_lock(); dev = dev_get_by_index_rcu(net, ifindex); |