| Message ID | 20210202193408.1171634-1-weiwan@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net-next] tcp: use a smaller percpu_counter batch size for sk_alloc | expand |
Hello: This patch was applied to netdev/net-next.git (refs/heads/master): On Tue, 2 Feb 2021 11:34:08 -0800 you wrote: > Currently, a percpu_counter with the default batch size (2*nr_cpus) is > used to record the total # of active sockets per protocol. This means > sk_sockets_allocated_read_positive() could be off by +/-2*(nr_cpus^2). > This under/over-estimation could lead to wrong memory suppression > conditions in __sk_raise_mem_allocated(). > Fix this by using a more reasonable fixed batch size of 16. > > [...] Here is the summary with links: - [net-next] tcp: use a smaller percpu_counter batch size for sk_alloc https://git.kernel.org/netdev/net-next/c/f5a5589c7250 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/include/net/sock.h b/include/net/sock.h index 129d200bccb4..690e496a0e79 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1350,14 +1350,18 @@ sk_memory_allocated_sub(struct sock *sk, int amt) atomic_long_sub(amt, sk->sk_prot->memory_allocated); } +#define SK_ALLOC_PERCPU_COUNTER_BATCH 16 + static inline void sk_sockets_allocated_dec(struct sock *sk) { - percpu_counter_dec(sk->sk_prot->sockets_allocated); + percpu_counter_add_batch(sk->sk_prot->sockets_allocated, -1, + SK_ALLOC_PERCPU_COUNTER_BATCH); } static inline void sk_sockets_allocated_inc(struct sock *sk) { - percpu_counter_inc(sk->sk_prot->sockets_allocated); + percpu_counter_add_batch(sk->sk_prot->sockets_allocated, 1, + SK_ALLOC_PERCPU_COUNTER_BATCH); } static inline u64
Currently, a percpu_counter with the default batch size (2*nr_cpus) is used to record the total # of active sockets per protocol. This means sk_sockets_allocated_read_positive() could be off by +/-2*(nr_cpus^2). This under/over-estimation could lead to wrong memory suppression conditions in __sk_raise_mem_allocated(). Fix this by using a more reasonable fixed batch size of 16. See related commit cf86a086a180 ("net/dst: use a smaller percpu_counter batch for dst entries accounting") that addresses a similar issue. Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> --- include/net/sock.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)