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authorPaul Menage <menage@google.com>2008-04-29 01:00:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 08:06:11 -0700
commit786083667e0ced85ce17c4c0b6c57a9f47c5b9f2 (patch)
tree4519c51c3ec7d093fe0bafbbd67204a6f7b773b3 /Documentation/cpusets.txt
parentaddf2c739d9015d3e9c0500b58a3af051cd58ea7 (diff)
downloadop-kernel-dev-786083667e0ced85ce17c4c0b6c57a9f47c5b9f2.zip
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Cpuset hardwall flag: add a mem_hardwall flag to cpusets
This flag provides the hardwalling properties of mem_exclusive, without enforcing the exclusivity. Either mem_hardwall or mem_exclusive is sufficient to prevent GFP_KERNEL allocations from passing outside the cpuset's assigned nodes. Signed-off-by: Paul Menage <menage@google.com> Acked-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/cpusets.txt')
-rw-r--r--Documentation/cpusets.txt26
1 files changed, 14 insertions, 12 deletions
diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt
index aa854b9..fb7b361 100644
--- a/Documentation/cpusets.txt
+++ b/Documentation/cpusets.txt
@@ -171,6 +171,7 @@ files describing that cpuset:
- memory_migrate flag: if set, move pages to cpusets nodes
- cpu_exclusive flag: is cpu placement exclusive?
- mem_exclusive flag: is memory placement exclusive?
+ - mem_hardwall flag: is memory allocation hardwalled
- memory_pressure: measure of how much paging pressure in cpuset
In addition, the root cpuset only has the following file:
@@ -222,17 +223,18 @@ If a cpuset is cpu or mem exclusive, no other cpuset, other than
a direct ancestor or descendent, may share any of the same CPUs or
Memory Nodes.
-A cpuset that is mem_exclusive restricts kernel allocations for
-page, buffer and other data commonly shared by the kernel across
-multiple users. All cpusets, whether mem_exclusive or not, restrict
-allocations of memory for user space. This enables configuring a
-system so that several independent jobs can share common kernel data,
-such as file system pages, while isolating each jobs user allocation in
-its own cpuset. To do this, construct a large mem_exclusive cpuset to
-hold all the jobs, and construct child, non-mem_exclusive cpusets for
-each individual job. Only a small amount of typical kernel memory,
-such as requests from interrupt handlers, is allowed to be taken
-outside even a mem_exclusive cpuset.
+A cpuset that is mem_exclusive *or* mem_hardwall is "hardwalled",
+i.e. it restricts kernel allocations for page, buffer and other data
+commonly shared by the kernel across multiple users. All cpusets,
+whether hardwalled or not, restrict allocations of memory for user
+space. This enables configuring a system so that several independent
+jobs can share common kernel data, such as file system pages, while
+isolating each job's user allocation in its own cpuset. To do this,
+construct a large mem_exclusive cpuset to hold all the jobs, and
+construct child, non-mem_exclusive cpusets for each individual job.
+Only a small amount of typical kernel memory, such as requests from
+interrupt handlers, is allowed to be taken outside even a
+mem_exclusive cpuset.
1.5 What is memory_pressure ?
@@ -707,7 +709,7 @@ Now you want to do something with this cpuset.
In this directory you can find several files:
# ls
-cpus cpu_exclusive mems mem_exclusive tasks
+cpus cpu_exclusive mems mem_exclusive mem_hardwall tasks
Reading them will give you information about the state of this cpuset:
the CPUs and Memory Nodes it can use, the processes that are using
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