Messages in this thread | | | Date | Tue, 20 Jun 2023 18:13:18 +0800 | Subject | Re: Re: [PATCH net-next] inet: Save one atomic op if no memcg to charge | From | Abel Wu <> |
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On 6/20/23 4:46 PM, Eric Dumazet wrote: > On Tue, Jun 20, 2023 at 5:04 AM Abel Wu <wuyun.abel@bytedance.com> wrote: >> >> On 6/19/23 6:08 PM, Eric Dumazet wrote: >>> On Mon, Jun 19, 2023 at 10:26 AM Abel Wu <wuyun.abel@bytedance.com> wrote: >>>> >>>> If there is no net-memcg associated with the sock, don't bother >>>> calculating its memory usage for charge. >>>> >>>> Signed-off-by: Abel Wu <wuyun.abel@bytedance.com> >>>> --- >>>> net/ipv4/inet_connection_sock.c | 18 +++++++++++------- >>>> 1 file changed, 11 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c >>>> index 65ad4251f6fd..73798282c1ef 100644 >>>> --- a/net/ipv4/inet_connection_sock.c >>>> +++ b/net/ipv4/inet_connection_sock.c >>>> @@ -706,20 +706,24 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) >>>> out: >>>> release_sock(sk); >>>> if (newsk && mem_cgroup_sockets_enabled) { >>>> - int amt; >>>> + int amt = 0; >>>> >>>> /* atomically get the memory usage, set and charge the >>>> * newsk->sk_memcg. >>>> */ >>>> lock_sock(newsk); >>>> >>>> - /* The socket has not been accepted yet, no need to look at >>>> - * newsk->sk_wmem_queued. >>>> - */ >>>> - amt = sk_mem_pages(newsk->sk_forward_alloc + >>>> - atomic_read(&newsk->sk_rmem_alloc)); >>>> mem_cgroup_sk_alloc(newsk); >>>> - if (newsk->sk_memcg && amt) >>>> + if (newsk->sk_memcg) { >>>> + /* The socket has not been accepted yet, no need >>>> + * to look at newsk->sk_wmem_queued. >>>> + */ >>>> + amt = sk_mem_pages(newsk->sk_forward_alloc + >>>> + atomic_read(&newsk->sk_rmem_alloc)); >>>> + >>>> + } >>>> + >>>> + if (amt) >>>> mem_cgroup_charge_skmem(newsk->sk_memcg, amt, >>>> GFP_KERNEL | __GFP_NOFAIL); >>> >>> This looks correct, but claiming reading an atomic_t is an 'atomic op' >>> is a bit exaggerated. >> >> Yeah, shall I change subject to 'inet: Skip usage calculation if no >> memcg to charge'? Or do you have any suggestions? > > I would call this a cleanup or refactoring, maybe...
Alright, I have changed to 'cleanup', please take a look at v2.
Yet I have another question about this condition: 'if (newsk && mem_cgroup_sockets_enabled)' IMHO in the scope of cgroup v1, 'mem_cgroup_sockets_enabled' doesn't imply socket accounting enabled for current's memcg. As the listening socket and the newly accepted socket are processing same traffic, can we make this condition more specific like this: 'if (newsk && mem_cgroup_sockets_enabled && sk->sk_memcg)' would you mind shedding some light please?
Thanks! Abel
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