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