On Tue, 29 Nov 2011 21:56:54 -0200
Glauber Costa <glommer@xxxxxxxxxxxxx> wrote:
> The goal of this work is to move the memory pressure tcp
> controls to a cgroup, instead of just relying on global
> conditions.
>
> To avoid excessive overhead in the network fast paths,
> the code that accounts allocated memory to a cgroup is
> hidden inside a static_branch(). This branch is patched out
> until the first non-root cgroup is created. So when nobody
> is using cgroups, even if it is mounted, no significant performance
> penalty should be seen.
>
> This patch handles the generic part of the code, and has nothing
> tcp-specific.
>
> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> Acked-by: Kirill A. Shutemov<kirill@xxxxxxxxxxxxx>
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxx>
> CC: David S. Miller <davem@xxxxxxxxxxxxx>
> CC: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> CC: Eric Dumazet <eric.dumazet@xxxxxxxxx>
<snip>
> +extern struct jump_label_key memcg_socket_limit_enabled;
> static inline bool sk_has_memory_pressure(const struct sock *sk)
> {
> return sk->sk_prot->memory_pressure != NULL;
> @@ -873,6 +900,17 @@ static inline bool sk_under_memory_pressure(const struct sock *sk)
> {
> if (!sk->sk_prot->memory_pressure)
> return false;
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> + if (static_branch(&memcg_socket_limit_enabled)) {
> + struct cg_proto *cg_proto = sk->sk_cgrp;
> +
> + if (!cg_proto)
> + goto nocgroup;
> + return !!*cg_proto->memory_pressure;
> + } else
What is dangling 'else' for ?
> +nocgroup:
> +#endif
> +
> return !!*sk->sk_prot->memory_pressure;
> }
>
> @@ -880,52 +918,176 @@ static inline void sk_leave_memory_pressure(struct sock *sk)
> {
> int *memory_pressure = sk->sk_prot->memory_pressure;
>
> - if (memory_pressure && *memory_pressure)
> + if (!memory_pressure)
> + return;
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> + if (static_branch(&memcg_socket_limit_enabled)) {
> + struct cg_proto *cg_proto = sk->sk_cgrp;
> +
> + if (!cg_proto)
> + goto nocgroup;
> +
> + for (; cg_proto; cg_proto = cg_proto->parent)
> + if (*cg_proto->memory_pressure)
> + *cg_proto->memory_pressure = 0;
> + }
> +nocgroup:
> +#endif
Hmm..can't we have a good way for avoiding this #ifdef ?
I guess... as NUMA_BUILD macro in page_alloc.c, you can define
if (HAS_KMEM_LIMIT && static_branch(&.....)).
For example,
==
#include <stdio.h>
#define HAS_SPECIAL 0
int main(int argc, char *argv[])
{
if (HAS_SPECIAL)
call();
printf("Hey!");
}
==
This can be compiled.
So. I guess...
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
#define do_memcg_kmem_account static_branch(&memcg_socket_limit_enabled)
#else
#define do_memcg_kmem_account 0
#endif
maybe good.(not tested.)
BTW, I don't think 'goto nocgroup' is good.
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 3becb24..12a08bf 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -377,6 +377,40 @@ enum mem_type {
> #define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2
> #define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT)
>
> +static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
> +{
> + return (memcg == root_mem_cgroup);
> +}
> +
Why do you need this move of definition ?
Thanks,
-Kame
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