[Devel] Re: [PATCH v7 02/10] foundations of per-cgroup memory pressure controlling.

KAMEZAWA Hiroyuki kamezawa.hiroyu at jp.fujitsu.com
Tue Nov 29 16:43:05 PST 2011


On Tue, 29 Nov 2011 21:56:53 -0200
Glauber Costa <glommer at parallels.com> wrote:

> This patch replaces all uses of struct sock fields' memory_pressure,
> memory_allocated, sockets_allocated, and sysctl_mem to acessor
> macros. Those macros can either receive a socket argument, or a mem_cgroup
> argument, depending on the context they live in.
> 
> Since we're only doing a macro wrapping here, no performance impact at all is
> expected in the case where we don't have cgroups disabled.
> 
> Signed-off-by: Glauber Costa <glommer at parallels.com>
> CC: David S. Miller <davem at davemloft.net>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu at jp.fujitsu.com>
> CC: Eric W. Biederman <ebiederm at xmission.com>
> CC: Eric Dumazet <eric.dumazet at gmail.com>
<snip>

> +static inline bool
> +memcg_memory_pressure(struct proto *prot, struct mem_cgroup *memcg)
> +{
> +	if (!prot->memory_pressure)
> +		return false;
> +	return !!prot->memory_pressure;
> +}

I think you should take a deep breath and write patech relaxedly, and do enough test.

This should be

	return !!*prot->memory_pressure;

BTW, I don't like to receive tons of everyday-update even if you're in hurry.





>  static void proto_seq_printf(struct seq_file *seq, struct proto *proto)
>  {
> +	struct mem_cgroup *memcg = mem_cgroup_from_task(current);
> +
>  	seq_printf(seq, "%-9s %4u %6d  %6ld   %-3s %6u   %-3s  %-10s "
>  			"%2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c\n",
>  		   proto->name,
>  		   proto->obj_size,
>  		   sock_prot_inuse_get(seq_file_net(seq), proto),
> -		   proto->memory_allocated != NULL ? atomic_long_read(proto->memory_allocated) : -1L,
> -		   proto->memory_pressure != NULL ? *proto->memory_pressure ? "yes" : "no" : "NI",
> +		   sock_prot_memory_allocated(proto, memcg),
> +		   sock_prot_memory_pressure(proto, memcg),

I wonder I should say NO, here. (Networking guys are ok ??)

IIUC, this means there is no way to see aggregated sockstat of all system.
And the result depends on the cgroup which the caller is under control.

I think you should show aggregated sockstat(global + per-memcg) here and 
show per-memcg ones via /cgroup interface or add private_sockstat to show
per cgroup summary.

Thanks,
-Kame




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