Commit 931f3f4b authored Jan 14, 2016 by Johannes Weiner Committed by Linus Torvalds Jan 14, 2016

net: tcp_memcontrol: remove bogus hierarchy pressure propagation



When a cgroup currently breaches its socket memory limit, it enters
memory pressure mode for itself and its *ancestors*.  This throttles
transmission in unrelated sibling and cousin subtrees that have nothing
to do with the breached limit.

On the contrary, breaching a limit should make that group and its
*children* enter memory pressure mode.  But this happens already, albeit
lazily: if an ancestor limit is breached, siblings will enter memory
pressure on their own once the next packet arrives for them.

So no additional hierarchy code is needed.  Remove the bogus stuff.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 8c2c2358

include/net/sock.h

+4 −15

Original line number	Diff line number	Diff line
		@@ -1155,14 +1155,8 @@ static inline void sk_leave_memory_pressure(struct sock *sk)
		if (*memory_pressure)
		*memory_pressure = 0;

		if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
		struct cg_proto *cg_proto = sk->sk_cgrp;
		struct proto *prot = sk->sk_prot;

		for (; cg_proto; cg_proto = parent_cg_proto(prot, cg_proto))
		cg_proto->memory_pressure = 0;
		}

		if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
		sk->sk_cgrp->memory_pressure = 0;
		}

		static inline void sk_enter_memory_pressure(struct sock *sk)
		@@ -1170,13 +1164,8 @@ static inline void sk_enter_memory_pressure(struct sock *sk)
		if (!sk->sk_prot->enter_memory_pressure)
		return;

		if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
		struct cg_proto *cg_proto = sk->sk_cgrp;
		struct proto *prot = sk->sk_prot;

		for (; cg_proto; cg_proto = parent_cg_proto(prot, cg_proto))
		cg_proto->memory_pressure = 1;
		}
		if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
		sk->sk_cgrp->memory_pressure = 1;

		sk->sk_prot->enter_memory_pressure(sk);
		}

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