tcp: seq_file: Replace listening_hash with lhash2
This patch moves the tcp seq_file iteration on listeners from the port only listening_hash to the port+addr lhash2. When iterating from the bpf iter, the next patch will need to lock the socket such that the bpf iter can call setsockopt (e.g. to change the TCP_CONGESTION). To avoid locking the bucket and then locking the sock, the bpf iter will first batch some sockets from the same bucket and then unlock the bucket. If the bucket size is small (which usually is), it is easier to batch the whole bucket such that it is less likely to miss a setsockopt on a socket due to changes in the bucket. However, the port only listening_hash could have many listeners hashed to a bucket (e.g. many individual VIP(s):443 and also multiple by the number of SO_REUSEPORT). We have seen bucket size in tens of thousands range. Also, the chance of having changes in some popular port buckets (e.g. 443) is also high. The port+addr lhash2 was introduced to solve this large listener bucket issue. Also, the listening_hash usage has already been replaced with lhash2 in the fast path inet[6]_lookup_listener(). This patch follows the same direction on moving to lhash2 and iterates the lhash2 instead of listening_hash. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210701200606.1035783-1-kafai@fb.com
Showing
Please register or sign in to comment