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- 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 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
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