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authorDavid Woodhouse <David.Woodhouse@intel.com>2012-08-22 12:54:55 +0100
committerDavid Woodhouse <David.Woodhouse@intel.com>2012-08-22 12:55:43 +0100
commit2361f738b67ab7f1152187fa3d321a09b7c95c09 (patch)
treeeddf2b958215b668b9b871b6b59bc76c67a47751 /Documentation/cgroups/hugetlb.txt
parent4800399e335658aae632f587f6759a860f584804 (diff)
parentd9875690d9b89a866022ff49e3fcea892345ad92 (diff)
downloadtalos-op-linux-2361f738b67ab7f1152187fa3d321a09b7c95c09.tar.gz
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Merge tag 'v3.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux
Having missed the merge window, update to 3.6-rc2 to avoid conflicts with new patches. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
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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 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
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