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Revision c4b5fd3fb2058b650447372472ad24e2a989f9f6 authored by Linus Torvalds on 09 July 2015, 20:35:39 UTC, committed by Linus Torvalds on 09 July 2015, 20:35:39 UTC 
Merge branch 'hpfs-patches' (patches from Mikulas Patocka)
 
Merge hpfs updates from Mikulas Patocka.

Mainly fstrim support, with some minor other cleanups.

These were actually sent during the merge window, but I wanted to wait
for the FSTRIM compat handling cleanup before applying them.  Mikulas
sent that earlier today.

* emailed patches from Mikulas Patocka <mikulas@twibright.com>:
  hpfs: hpfs_error: Remove static buffer, use vsprintf extension %pV instead
  hpfs: kstrdup() out of memory handling
  hpfs: Remove unessary cast
  hpfs: add fstrim support
2 parent s 4c0a9f7 + a28e4b2
Raw File
hugetlb.txt 
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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