| Re: [PATCH v7 04/10] tcp memory pressure controls [message #44376 is a reply to message #44366] |
Mon, 05 December 2011 02:01   |
KAMEZAWA Hiroyuki
Messages: 463
Registered: September 2006
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Senior Member |
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On Fri, 2 Dec 2011 15:57:28 -0200
Glauber Costa <glommer@parallels.com> wrote:
> On 11/29/2011 11:49 PM, KAMEZAWA Hiroyuki wrote:
> >
> >> -static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
> >> +struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
> >> {
> >> return container_of(cgroup_subsys_state(cont,
> >> mem_cgroup_subsys_id), struct mem_cgroup,
> >> @@ -4717,14 +4732,27 @@ static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
> >>
> >> ret = cgroup_add_files(cont, ss, kmem_cgroup_files,
> >> ARRAY_SIZE(kmem_cgroup_files));
> >> +
> >> + if (!ret)
> >> + ret = mem_cgroup_sockets_init(cont, ss);
> >> return ret;
> >> };
> >
> > You does initizalication here. The reason what I think is
> > 1. 'proto_list' is not available at createion of root cgroup and
> > you need to delay set up until mounting.
> >
> > If so, please add comment or find another way.
> > This seems not very clean to me.
>
> Yes, we do can run into some ordering issues. A part of the
> initialization can be done earlier. But I preferred to move it all later
> instead of creating two functions for it. But I can change that if you
> want, no big deal.
>
Hmm. please add comments about the 'issue'. It will help readers.
> >> + tcp->tcp_prot_mem[0] = sysctl_tcp_mem[0];
> >> + tcp->tcp_prot_mem[1] = sysctl_tcp_mem[1];
> >> + tcp->tcp_prot_mem[2] = sysctl_tcp_mem[2];
> >> + tcp->tcp_memory_pressure = 0;
> >
> > Question:
> >
> > Is this value will be updated when an admin chages sysctl ?
>
> yes.
>
> > I guess, this value is set at system init script or some which may
> > happen later than mounting cgroup.
> > I don't like to write a guideline 'please set sysctl val before
> > mounting cgroup'
>
> Agreed.
>
> This code is in patch 6 (together with the limiting):
>
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> + rcu_read_lock();
> + memcg = mem_cgroup_from_task(current);
> +
> + tcp_prot_mem(memcg, vec[0], 0);
> + tcp_prot_mem(memcg, vec[1], 1);
> + tcp_prot_mem(memcg, vec[2], 2);
> + rcu_read_unlock();
> +#endif
>
> tcp_prot_mem is just a wrapper around the assignment so we can access
> memcg's inner fields.
>
Ok. sysctl and cgroup are updated at the same time.
thank you.
-Kame
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