[lxc-devel] Memory Resources

KAMEZAWA Hiroyuki kamezawa.hiroyu at jp.fujitsu.com
Sun Aug 23 17:27:39 PDT 2009


On Sun, 23 Aug 2009 23:12:24 +0200
Krzysztof Taraszka <krzysztof.taraszka at gnuhosting.net> wrote:

> :) excelent :)
> 
> my ugly patch printing right now undefinied data but the idea was the same
> :)
> how about memsw_limit for swap? :>
> I am looking for swap usage statistics from cgroup right now from
> memcontrol.c :) but as you did the idea is good and should be add to the
> kernel and lxc-tools :)
> 

Hmm, why meminfo is necessary ? For cheating top/free/... etc ?



Thanks,
-Kame



> 
> 2009/8/23 Daniel Lezcano <daniel.lezcano at free.fr>
> 
> > Krzysztof Taraszka wrote:
> >
> >> 2009/8/23 Daniel Lezcano <daniel.lezcano at free.fr>
> >>
> >>  Krzysztof Taraszka wrote:
> >>>
> >>>  2009/8/23 Krzysztof Taraszka <krzysztof.taraszka at gnuhosting.net>
> >>>>
> >>>>
> >>>>
> >>>>  2009/8/23 Krzysztof Taraszka <krzysztof.taraszka at gnuhosting.net>
> >>>>>
> >>>>>
> >>>>>
> >>>>>  2009/8/23 Daniel Lezcano <daniel.lezcano at free.fr>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>  Krzysztof Taraszka wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>  2009/8/23 Daniel Lezcano <daniel.lezcano at free.fr>
> >>>>>>>>
> >>>>>>>>  Krzysztof Taraszka wrote:
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>   Hello,
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>  I am running lxc on my debian unstable sandbox and I have a few
> >>>>>>>>>> question
> >>>>>>>>>> about memory managament inside linux containers based on lxc
> >>>>>>>>>> project.
> >>>>>>>>>>
> >>>>>>>>>> I have got linux kernel 2.6.30.5 with enabled :
> >>>>>>>>>>
> >>>>>>>>>> +Resource counter
> >>>>>>>>>> ++ Memory Resource Controller for Control Groups
> >>>>>>>>>>  +++ Memory Resource Controller Swap Extension(EXPERIMENTAL)
> >>>>>>>>>>
> >>>>>>>>>> lxc-checkconfig pass all checks.
> >>>>>>>>>>
> >>>>>>>>>> I read about cgroups memory managament
> >>>>>>>>>> (Documentation/cgroups/memory.txt)
> >>>>>>>>>> and I tried to pass those value to my debian sandbox.
> >>>>>>>>>>
> >>>>>>>>>> And...
> >>>>>>>>>> 'free -m' and 'top/htop' still show all available memory inside
> >>>>>>>>>> container
> >>>>>>>>>> (also If I set 32M for lxc.cgroup.memory.limit_in_bytes and
> >>>>>>>>>> lxc.cgroup.memory.usage_in_bytes; and 64M for
> >>>>>>>>>> lxc.cgroup.memory.memsw.usage_in_bytes and
> >>>>>>>>>> lxc.cgroup.memory.memsw.limit_in_bytes free and top show all
> >>>>>>>>>> resources).
> >>>>>>>>>>
> >>>>>>>>>> What I did wrong? Does the container always show all available
> >>>>>>>>>> memory
> >>>>>>>>>> resources  without cgroup limitations?
> >>>>>>>>>>
> >>>>>>>>>>  At the first glance I would say the configuration is correct.
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>  But AFAIR, the memory cgroup is not isolated, if you specify 32MB
> >>>>>>>>> you
> >>>>>>>>> will
> >>>>>>>>> see all the memory available on the system either if you are not
> >>>>>>>>> allowed to
> >>>>>>>>> use more than 32MB. If you create a program which allocates 64MB
> >>>>>>>>> within
> >>>>>>>>> a
> >>>>>>>>> container configured with 32MB, and you "touch" the pages (may be
> >>>>>>>>> that
> >>>>>>>>> can
> >>>>>>>>> be done with one mmap call with the MAP_POPULATE option), you
> >>>>>>>>> should
> >>>>>>>>> see the
> >>>>>>>>> application swapping and the "memory.failcnt" increasing.
> >>>>>>>>>
> >>>>>>>>> IMHO, showing all the memory available for the system instead of
> >>>>>>>>> showing
> >>>>>>>>> the allowed memory with the cgroup is weird but maybe there is a
> >>>>>>>>> good
> >>>>>>>>> reason
> >>>>>>>>> to do that.
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>  Thank you Daniel for your reply.
> >>>>>>>> I think that LXC should isolate memory available for containers like
> >>>>>>>> Vserver
> >>>>>>>> or FreeVPS do (memory + swap) if .cgroup.memory.* and
> >>>>>>>> lxc.cgroup.memory.memsw.* is set.
> >>>>>>>> Is there any possibility to make a patch for linux kernel /
> >>>>>>>> lxc-tools
> >>>>>>>> to
> >>>>>>>> show the limitations inside cointainers propertly? I think is a good
> >>>>>>>> idea
> >>>>>>>> and it should be apply as soon as possible.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>  Maybe a solution can be to add a new memory.meminfo file in the
> >>>>>>> same
> >>>>>>> format than /proc/meminfo, so it will be possible to mount --bind
> >>>>>>> /cgroup/foo/memory.meminfo to /proc/meminfo for the container.
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>  Yes, I thought the same. This should allow the user-space tools
> >>>>>> based on
> >>>>>> /proc/meminfo (such as comand line "free") show limited information :)
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>  Hmmm... does the memory.stat is a good start point for make new one
> >>>>> object
> >>>>> memory.meminfo similar to /proc/meminfo? If so, I can play by my self
> >>>>> with
> >>>>> lxc-tools code.
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>> Hmmm... Daniel, I have got a question (that do I thinking in the right
> >>>> way).
> >>>> here is an output from /proc/meminfo from openvz:
> >>>>
> >>>>
> >>>> MemTotal:             262144 kB
> >>>> MemFree:            232560 kB
> >>>> Buffers:             0 kB
> >>>> Cached:            0 kB
> >>>> SwapCached:        0 kB
> >>>> Active:            0 kB
> >>>> Inactive:            0 kB
> >>>> HighTotal:            0 kB
> >>>> HighFree:            0 kB
> >>>> LowTotal:             262144 kB
> >>>> LowFree:            232560 kB
> >>>> SwapTotal:        0 kB
> >>>> SwapFree:        0 kB
> >>>> Dirty:             0 kB
> >>>> Writeback:        0 kB
> >>>> AnonPages:        0 kB
> >>>> Mapped:            0 kB
> >>>> Slab:                0 kB
> >>>> SReclaimable:            0 kB
> >>>> SUnreclaim:              0 kB
> >>>> PageTables:              0 kB
> >>>> NFS_Unstable:           0 kB
> >>>> Bounce:                  0 kB
> >>>> WritebackTmp:            0 kB
> >>>> CommitLimit:             0 kB
> >>>> Committed_AS:            0 kB
> >>>> VmallocTotal:            0 kB
> >>>> VmallocUsed:             0 kB
> >>>> VmallocChunk:            0 kB
> >>>> HugePages_Total:    0
> >>>> HugePages_Free:    0
> >>>> HugePages_Rsvd:   0
> >>>> HugePages_Surp:    0
> >>>> Hugepagesize:         2048 kB
> >>>>
> >>>> most of values are 0.
> >>>>
> >>>> I have an question about SwapTotal and SwapFree for LXC.
> >>>> As I thinking that:
> >>>>
> >>>> MemTotal might be: hierarchical_memory_limit
> >>>> MemFree might be: hierarchical_memory_limit - cache
> >>>>
> >>>>
> >>>>  I am not a memory expert, but isn't MemFree : hierarchical_memory_limit
> >>> -
> >>> rss ?
> >>>
> >>>  the
> >>>>
> >>>> SwapTotal might be: hierarchical_memsw_limit
> >>>> SwapFree might be: hierarchical_memsw_limit - rss
> >>>>
> >>>> rss - # of bytes of anonymous and swap cache memory
> >>>> I don't know at all that hierarchical_memsw_limit is an good value for
> >>>> swap
> >>>> total, because as I read it is a mem+swap at all.
> >>>>
> >>>> Does the lxc memory.meminfo might look like above? Where can I get the
> >>>> Hugepagesize?
> >>>>
> >>>>
> >>>>  Right, I agree most of the interesting information to create a
> >>> memory.meminfo is already there in another file and another format.
> >>> Probably
> >>> some informations in memory.stat can be moved to memory.meminfo and this
> >>> one
> >>> can be step by step filled with cgroup memory statistic informations.
> >>> IMO,
> >>> if the memory controller displays memory statistics like a proc/meminfo
> >>> file
> >>> format, that will make consistency for these informations and make
> >>> trivial
> >>> the isolation/virtualization with a simple mount-bind.
> >>>
> >>>
> >>>
> >>>  Hmm..
> >> might be. Right now I am looking for and writing new function in
> >> mm/memcontrol.c file for writing some stats in memory.meminfo file for
> >> tests.
> >> Dirty and ugly part of code, but if it will work as we thought
> >> (mount-bind)
> >> and as you wrote above, that will be very simple.
> >> I am going to look how does the /proc/meminfo is doing by the openvz.
> >> mm/memcontrol.c was wrote by xemul from openvz and balbir from ibm.
> >> If I am thinking in the right way, guys from openvz made their own patch
> >> for
> >> meminfo based on the mm/memcontrol.c. If I am wrong - where do they taking
> >> meminfo data? :)
> >>
> >
> > I did this ugly patch patch for MemTotal/MemFree - maybe wrong :)
> >
> > Index: linux-2.6/mm/memcontrol.c
> > ===================================================================
> > --- linux-2.6.orig/mm/memcontrol.c      2009-06-23 12:00:52.000000000 +0200
> > +++ linux-2.6/mm/memcontrol.c   2009-08-23 22:49:02.000000000 +0200
> > @@ -2200,6 +2200,27 @@ static int mem_cgroup_swappiness_write(s
> >  }
> >
> >
> > +static int mem_cgroup_meminfo(struct cgroup *cgrp, struct cftype *cft,
> > +                             struct seq_file *seq)
> > +{
> > +#define K(x) ((x) << 10)
> > +
> > +       struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cgrp);
> > +       struct mcs_total_stat mystat = { };
> > +       unsigned long long limit, memsw_limit;
> > +
> > +       mem_cgroup_get_local_stat(mem_cont, &mystat);
> > +       memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit);
> > +
> > +       seq_printf(seq,
> > +                  "MemTotal:       %8llu kB\n"
> > +                  "MemFree:        %8llu kB\n",
> > +                  limit / 1024, (limit - mystat.stat[MCS_RSS]) / 1024);
> > +
> > +       return 0;
> > +#undef K
> > +}
> > +
> >  static struct cftype mem_cgroup_files[] = {
> >        {
> >                .name = "usage_in_bytes",
> > @@ -2242,6 +2263,10 @@ static struct cftype mem_cgroup_files[]
> >                .read_u64 = mem_cgroup_swappiness_read,
> >                .write_u64 = mem_cgroup_swappiness_write,
> >        },
> > +       {
> > +               .name = "meminfo",
> > +               .read_seq_string = mem_cgroup_meminfo,
> > +       },
> >  };
> >
> >  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> >
> >
> > With the lxc tools I did:
> >
> >        lxc-execute -n foo /bin/bash
> >        echo 268435456 > /cgroup/foo/memory.limit_in_bytes
> >        mount --bind /cgroup/foo/memory.meminfo /proc/meminfo
> >        for i in $(seq 1 100); do sleep 3600 & done
> >
> > And the result for "free" is:
> >
> > free:
> >
> >             total       used       free     shared    buffers     cached
> > Mem:        262144       9692     252452          0          0          0
> > -/+ buffers/cache:       9692     252452
> > Swap:            0          0          0
> >
> >
> > and for "top":
> >
> > top - 22:57:37 up 8 min,  1 user,  load average: 0.00, 0.02, 0.00
> > Tasks: 104 total,   1 running, 103 sleeping,   0 stopped,   0 zombie
> > Cpu(s):  0.3%us,  1.0%sy,  0.0%ni, 98.4%id,  0.0%wa,  0.0%hi,  0.3%si,
> > 0.0%st
> > Mem:    262144k total,     9864k used,   252280k free,        0k buffers
> > Swap:        0k total,        0k used,        0k free,        0k cached
> >
> >  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> >  337 root      20   0 14748 1132  872 R  1.0  0.4   0:00.24 top
> >    1 root      20   0  8136  484  408 S  0.0  0.2   0:00.00 lxc-init
> >    2 root      20   0 89980 1724 1348 S  0.0  0.7   0:00.70 bash
> >   25 root      20   0 86916  612  524 S  0.0  0.2   0:00.00 sleep
> >  232 root      20   0 86916  616  524 S  0.0  0.2   0:00.00 sleep
> >  233 root      20   0 86916  612  524 S  0.0  0.2   0:00.00 sleep
> >  234 root      20   0 86916  612  524 S  0.0  0.2   0:00.00 sleep
> >  235 root      20   0 86916  612  524 S  0.0  0.2   0:00.00 sleep
> > .....
> >
> >
> > :)
> >
> >
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