lkml.org 
[lkml]   [2011]   [Sep]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v3 1/7] Basic kernel memory functionality for the Memory Controller
    From
    On Wed, Sep 21, 2011 at 7:53 AM, Glauber Costa <glommer@parallels.com> wrote:
    >
    > Hi people,
    >
    > Any insights on this series?
    > Kame, is it inline with your expectations ?
    >
    > Thank you all
    >
    > On 09/18/2011 09:56 PM, Glauber Costa wrote:
    >>
    >> This patch lays down the foundation for the kernel memory component
    >> of the Memory Controller.
    >>
    >> As of today, I am only laying down the following files:
    >>
    >>  * memory.independent_kmem_limit
    >>  * memory.kmem.limit_in_bytes (currently ignored)
    >>  * memory.kmem.usage_in_bytes (always zero)
    >>
    >> Signed-off-by: Glauber Costa<glommer@parallels.com>
    >> CC: Paul Menage<paul@paulmenage.org>
    >> CC: Greg Thelen<gthelen@google.com>
    >> ---
    >>  Documentation/cgroups/memory.txt |   30 +++++++++-
    >>  init/Kconfig                     |   11 ++++
    >>  mm/memcontrol.c                  |  115 ++++++++++++++++++++++++++++++++++++--
    >>  3 files changed, 148 insertions(+), 8 deletions(-)
    >>
    >> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
    >> index 6f3c598..6f1954a 100644
    >> --- a/Documentation/cgroups/memory.txt
    >> +++ b/Documentation/cgroups/memory.txt
    >> @@ -44,8 +44,9 @@ Features:
    >>   - oom-killer disable knob and oom-notifier
    >>   - Root cgroup has no limit controls.
    >>
    >> - Kernel memory and Hugepages are not under control yet. We just manage
    >> - pages on LRU. To add more controls, we have to take care of performance.
    >> + Hugepages is not under control yet. We just manage pages on LRU. To add more
    >> + controls, we have to take care of performance. Kernel memory support is work
    >> + in progress, and the current version provides basically functionality.
    >>
    >>  Brief summary of control files.
    >>
    >> @@ -56,8 +57,11 @@ Brief summary of control files.
    >>                                 (See 5.5 for details)
    >>   memory.memsw.usage_in_bytes   # show current res_counter usage for memory+Swap
    >>                                 (See 5.5 for details)
    >> + memory.kmem.usage_in_bytes     # show current res_counter usage for kmem only.
    >> +                                (See 2.7 for details)
    >>   memory.limit_in_bytes                 # set/show limit of memory usage
    >>   memory.memsw.limit_in_bytes   # set/show limit of memory+Swap usage
    >> + memory.kmem.limit_in_bytes     # if allowed, set/show limit of kernel memory
    >>   memory.failcnt                        # show the number of memory usage hits limits
    >>   memory.memsw.failcnt          # show the number of memory+Swap hits limits
    >>   memory.max_usage_in_bytes     # show max memory usage recorded
    >> @@ -72,6 +76,9 @@ Brief summary of control files.
    >>   memory.oom_control            # set/show oom controls.
    >>   memory.numa_stat              # show the number of memory usage per numa node
    >>
    >> + memory.independent_kmem_limit  # select whether or not kernel memory limits are
    >> +                                  independent of user limits
    >> +
    >>  1. History
    >>
    >>  The memory controller has a long history. A request for comments for the memory
    >> @@ -255,6 +262,25 @@ When oom event notifier is registered, event will be delivered.
    >>    per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by
    >>    zone->lru_lock, it has no lock of its own.
    >>
    >> +2.7 Kernel Memory Extension (CONFIG_CGROUP_MEM_RES_CTLR_KMEM)
    >> +
    >> + With the Kernel memory extension, the Memory Controller is able to limit
    >> +the amount of kernel memory used by the system. Kernel memory is fundamentally
    >> +different than user memory, since it can't be swapped out, which makes it
    >> +possible to DoS the system by consuming too much of this precious resource.
    >> +Kernel memory limits are not imposed for the root cgroup.
    >> +
    >> +Memory limits as specified by the standard Memory Controller may or may not
    >> +take kernel memory into consideration. This is achieved through the file
    >> +memory.independent_kmem_limit. A Value different than 0 will allow for kernel
    >> +memory to be controlled separately.
    >> +
    >> +When kernel memory limits are not independent, the limit values set in
    >> +memory.kmem files are ignored.
    >> +
    >> +Currently no soft limit is implemented for kernel memory. It is future work
    >> +to trigger slab reclaim when those limits are reached.
    >> +

    Ying Han was also looking into this (cc'ing her)

    >>  3. User Interface
    >>
    >>  0. Configuration
    >> diff --git a/init/Kconfig b/init/Kconfig
    >> index d627783..49e5839 100644
    >> --- a/init/Kconfig
    >> +++ b/init/Kconfig
    >> @@ -689,6 +689,17 @@ config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
    >>          For those who want to have the feature enabled by default should
    >>          select this option (if, for some reason, they need to disable it
    >>          then swapaccount=0 does the trick).
    >> +config CGROUP_MEM_RES_CTLR_KMEM
    >> +       bool "Memory Resource Controller Kernel Memory accounting"
    >> +       depends on CGROUP_MEM_RES_CTLR
    >> +       default y
    >> +       help
    >> +         The Kernel Memory extension for Memory Resource Controller can limit
    >> +         the amount of memory used by kernel objects in the system. Those are
    >> +         fundamentally different from the entities handled by the standard
    >> +         Memory Controller, which are page-based, and can be swapped. Users of
    >> +         the kmem extension can use it to guarantee that no group of processes
    >> +         will ever exhaust kernel resources alone.
    >>
    >>  config CGROUP_PERF
    >>        bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
    >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
    >> index ebd1e86..d32e931 100644
    >> --- a/mm/memcontrol.c
    >> +++ b/mm/memcontrol.c
    >> @@ -73,7 +73,11 @@ static int really_do_swap_account __initdata = 0;
    >>  #define do_swap_account               (0)
    >>  #endif
    >>
    >> -
    >> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
    >> +int do_kmem_account __read_mostly = 1;
    >> +#else
    >> +#define do_kmem_account                0
    >> +#endif
    >>  /*
    >>   * Statistics for memory cgroup.
    >>   */
    >> @@ -270,6 +274,10 @@ struct mem_cgroup {
    >>         */
    >>        struct res_counter memsw;
    >>        /*
    >> +        * the counter to account for kmem usage.
    >> +        */
    >> +       struct res_counter kmem;
    >> +       /*
    >>         * Per cgroup active and inactive list, similar to the
    >>         * per zone LRU lists.
    >>         */
    >> @@ -321,6 +329,11 @@ struct mem_cgroup {
    >>         */
    >>        unsigned long   move_charge_at_immigrate;
    >>        /*
    >> +        * Should kernel memory limits be stabilished independently
    >> +        * from user memory ?
    >> +        */
    >> +       int             kmem_independent;
    >> +       /*
    >>         * percpu counter.
    >>         */
    >>        struct mem_cgroup_stat_cpu *stat;
    >> @@ -388,9 +401,14 @@ enum charge_type {
    >>  };
    >>
    >>  /* for encoding cft->private value on file */
    >> -#define _MEM                   (0)
    >> -#define _MEMSWAP               (1)
    >> -#define _OOM_TYPE              (2)
    >> +
    >> +enum mem_type {
    >> +       _MEM = 0,
    >> +       _MEMSWAP,
    >> +       _OOM_TYPE,
    >> +       _KMEM,
    >> +};
    >> +
    >>  #define MEMFILE_PRIVATE(x, val)       (((x)<<  16) | (val))
    >>  #define MEMFILE_TYPE(val)     (((val)>>  16)&  0xffff)
    >>  #define MEMFILE_ATTR(val)     ((val)&  0xffff)
    >> @@ -3943,10 +3961,15 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
    >>        u64 val;
    >>
    >>        if (!mem_cgroup_is_root(mem)) {
    >> +               val = 0;
    >> +               if (!mem->kmem_independent)
    >> +                       val = res_counter_read_u64(&mem->kmem, RES_USAGE);
    >>                if (!swap)
    >> -                       return res_counter_read_u64(&mem->res, RES_USAGE);
    >> +                       val += res_counter_read_u64(&mem->res, RES_USAGE);
    >>                else
    >> -                       return res_counter_read_u64(&mem->memsw, RES_USAGE);
    >> +                       val += res_counter_read_u64(&mem->memsw, RES_USAGE);
    >> +
    >> +               return val;
    >>        }
    >>
    >>        val = mem_cgroup_recursive_stat(mem, MEM_CGROUP_STAT_CACHE);
    >> @@ -3979,6 +4002,10 @@ static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
    >>                else
    >>                        val = res_counter_read_u64(&mem->memsw, name);
    >>                break;
    >> +       case _KMEM:
    >> +               val = res_counter_read_u64(&mem->kmem, name);
    >> +               break;
    >> +
    >>        default:
    >>                BUG();
    >>                break;
    >> @@ -4756,6 +4783,21 @@ static int mem_cgroup_reset_vmscan_stat(struct cgroup *cgrp,
    >>        return 0;
    >>  }
    >>
    >> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
    >> +static u64 kmem_limit_independent_read(struct cgroup *cont, struct cftype *cft)
    >> +{
    >> +       return mem_cgroup_from_cont(cont)->kmem_independent;
    >> +}
    >> +
    >> +static int kmem_limit_independent_write(struct cgroup *cont, struct cftype *cft,
    >> +                                       u64 val)
    >> +{
    >> +       cgroup_lock();
    >> +       mem_cgroup_from_cont(cont)->kmem_independent = !!val;
    >> +       cgroup_unlock();
    >> +       return 0;
    >> +}

    I know we have a lot of pending xxx_from_cont() and struct cgroup
    *cont, can we move it to memcg notation to be more consistent with our
    usage. There is a patch to convert old usage

    >> +#endif
    >>
    >>  static struct cftype mem_cgroup_files[] = {
    >>        {
    >> @@ -4877,6 +4919,47 @@ static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
    >>  }
    >>  #endif
    >>
    >> +
    >> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
    >> +static struct cftype kmem_cgroup_files[] = {
    >> +       {
    >> +               .name = "independent_kmem_limit",
    >> +               .read_u64 = kmem_limit_independent_read,
    >> +               .write_u64 = kmem_limit_independent_write,
    >> +       },
    >> +       {
    >> +               .name = "kmem.usage_in_bytes",
    >> +               .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
    >> +               .read_u64 = mem_cgroup_read,
    >> +       },
    >> +       {
    >> +               .name = "kmem.limit_in_bytes",
    >> +               .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
    >> +               .read_u64 = mem_cgroup_read,
    >> +       },
    >> +};
    >> +
    >> +static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
    >> +{
    >> +       struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
    >> +       int ret = 0;
    >> +
    >> +       if (!do_kmem_account)
    >> +               return 0;
    >> +
    >> +       if (!mem_cgroup_is_root(mem))
    >> +               ret = cgroup_add_files(cont, ss, kmem_cgroup_files,
    >> +                                       ARRAY_SIZE(kmem_cgroup_files));
    >> +       return ret;
    >> +};
    >> +
    >> +#else
    >> +static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
    >> +{
    >> +       return 0;
    >> +}
    >> +#endif
    >> +
    >>  static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
    >>  {
    >>        struct mem_cgroup_per_node *pn;
    >> @@ -5075,6 +5158,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
    >>        if (parent&&  parent->use_hierarchy) {
    >>                res_counter_init(&mem->res,&parent->res);
    >>                res_counter_init(&mem->memsw,&parent->memsw);
    >> +               res_counter_init(&mem->kmem,&parent->kmem);
    >>                /*
    >>                 * We increment refcnt of the parent to ensure that we can
    >>                 * safely access it on res_counter_charge/uncharge.
    >> @@ -5085,6 +5169,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
    >>        } else {
    >>                res_counter_init(&mem->res, NULL);
    >>                res_counter_init(&mem->memsw, NULL);
    >> +               res_counter_init(&mem->kmem, NULL);
    >>        }
    >>        mem->last_scanned_child = 0;
    >>        mem->last_scanned_node = MAX_NUMNODES;
    >> @@ -5129,6 +5214,10 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss,
    >>
    >>        if (!ret)
    >>                ret = register_memsw_files(cont, ss);
    >> +
    >> +       if (!ret)
    >> +               ret = register_kmem_files(cont, ss);
    >> +
    >>        return ret;
    >>  }
    >>
    >> @@ -5665,3 +5754,17 @@ static int __init enable_swap_account(char *s)
    >>  __setup("swapaccount=", enable_swap_account);
    >>
    >>  #endif
    >> +
    >> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
    >> +static int __init disable_kmem_account(char *s)
    >> +{
    >> +       /* consider enabled if no parameter or 1 is given */
    >> +       if (!strcmp(s, "1"))
    >> +               do_kmem_account = 1;
    >> +       else if (!strcmp(s, "0"))
    >> +               do_kmem_account = 0;
    >> +       return 1;
    >> +}
    >> +__setup("kmemaccount=", disable_kmem_account);
    >> +
    >> +#endif

    The infrastructure looks OK, we need better integration with
    statistics for kmem usage.

    Balbir Singh
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2011-09-22 05:19    [W:0.051 / U:1.384 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site