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    Subject[PATCH -V8 16/16] hugetlb/cgroup: add HugeTLB controller documentation
    Date
    From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    ---
    Documentation/cgroups/hugetlb.txt | 45 +++++++++++++++++++++++++++++++++++++
    1 file changed, 45 insertions(+)
    create mode 100644 Documentation/cgroups/hugetlb.txt

    diff --git a/Documentation/cgroups/hugetlb.txt b/Documentation/cgroups/hugetlb.txt
    new file mode 100644
    index 0000000..a9faaca
    --- /dev/null
    +++ b/Documentation/cgroups/hugetlb.txt
    @@ -0,0 +1,45 @@
    +HugeTLB Controller
    +-------------------
    +
    +The HugeTLB controller allows to limit the HugeTLB usage per control group and
    +enforces the controller limit during page fault. Since HugeTLB doesn't
    +support page reclaim, enforcing the limit at page fault time implies that,
    +the application will get SIGBUS signal if it tries to access HugeTLB pages
    +beyond its limit. This requires the application to know beforehand how much
    +HugeTLB pages it would require for its use.
    +
    +HugeTLB controller can be created by first mounting the cgroup filesystem.
    +
    +# mount -t cgroup -o hugetlb none /sys/fs/cgroup
    +
    +With the above step, the initial or the parent HugeTLB group becomes
    +visible at /sys/fs/cgroup. At bootup, this group includes all the tasks in
    +the system. /sys/fs/cgroup/tasks lists the tasks in this cgroup.
    +
    +New groups can be created under the parent group /sys/fs/cgroup.
    +
    +# cd /sys/fs/cgroup
    +# mkdir g1
    +# echo $$ > g1/tasks
    +
    +The above steps create a new group g1 and move the current shell
    +process (bash) into it.
    +
    +Brief summary of control files
    +
    + hugetlb.<hugepagesize>.limit_in_bytes # set/show limit of "hugepagesize" hugetlb usage
    + hugetlb.<hugepagesize>.max_usage_in_bytes # show max "hugepagesize" hugetlb usage recorded
    + hugetlb.<hugepagesize>.usage_in_bytes # show current res_counter usage for "hugepagesize" hugetlb
    + hugetlb.<hugepagesize>.failcnt # show the number of allocation failure due to HugeTLB limit
    +
    +For a system supporting two hugepage size (16M and 16G) the control
    +files include:
    +
    +hugetlb.16GB.limit_in_bytes
    +hugetlb.16GB.max_usage_in_bytes
    +hugetlb.16GB.usage_in_bytes
    +hugetlb.16GB.failcnt
    +hugetlb.16MB.limit_in_bytes
    +hugetlb.16MB.max_usage_in_bytes
    +hugetlb.16MB.usage_in_bytes
    +hugetlb.16MB.failcnt
    --
    1.7.10


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