aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/admin-guide/mm/numa_memory_policy.rst
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--Documentation/admin-guide/mm/numa_memory_policy.rst41
1 files changed, 31 insertions, 10 deletions
diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst
index 8463f5538fda..5a6afecbb0d0 100644
--- a/Documentation/admin-guide/mm/numa_memory_policy.rst
+++ b/Documentation/admin-guide/mm/numa_memory_policy.rst
@@ -245,6 +245,13 @@ MPOL_INTERLEAVED
address range or file. During system boot up, the temporary
interleaved system default policy works in this mode.
+MPOL_PREFERRED_MANY
+ This mode specifices that the allocation should be preferrably
+ satisfied from the nodemask specified in the policy. If there is
+ a memory pressure on all nodes in the nodemask, the allocation
+ can fall back to all existing numa nodes. This is effectively
+ MPOL_PREFERRED allowed for a mask rather than a single node.
+
NUMA memory policy supports the following optional mode flags:
MPOL_F_STATIC_NODES
@@ -253,10 +260,10 @@ MPOL_F_STATIC_NODES
nodes changes after the memory policy has been defined.
Without this flag, any time a mempolicy is rebound because of a
- change in the set of allowed nodes, the node (Preferred) or
- nodemask (Bind, Interleave) is remapped to the new set of
- allowed nodes. This may result in nodes being used that were
- previously undesired.
+ change in the set of allowed nodes, the preferred nodemask (Preferred
+ Many), preferred node (Preferred) or nodemask (Bind, Interleave) is
+ remapped to the new set of allowed nodes. This may result in nodes
+ being used that were previously undesired.
With this flag, if the user-specified nodes overlap with the
nodes allowed by the task's cpuset, then the memory policy is
@@ -364,19 +371,19 @@ follows:
2) for querying the policy, we do not need to take an extra reference on the
target task's task policy nor vma policies because we always acquire the
- task's mm's mmap_sem for read during the query. The set_mempolicy() and
- mbind() APIs [see below] always acquire the mmap_sem for write when
+ task's mm's mmap_lock for read during the query. The set_mempolicy() and
+ mbind() APIs [see below] always acquire the mmap_lock for write when
installing or replacing task or vma policies. Thus, there is no possibility
of a task or thread freeing a policy while another task or thread is
querying it.
3) Page allocation usage of task or vma policy occurs in the fault path where
- we hold them mmap_sem for read. Again, because replacing the task or vma
- policy requires that the mmap_sem be held for write, the policy can't be
+ we hold them mmap_lock for read. Again, because replacing the task or vma
+ policy requires that the mmap_lock be held for write, the policy can't be
freed out from under us while we're using it for page allocation.
4) Shared policies require special consideration. One task can replace a
- shared memory policy while another task, with a distinct mmap_sem, is
+ shared memory policy while another task, with a distinct mmap_lock, is
querying or allocating a page based on the policy. To resolve this
potential race, the shared policy infrastructure adds an extra reference
to the shared policy during lookup while holding a spin lock on the shared
@@ -401,7 +408,7 @@ follows:
Memory Policy APIs
==================
-Linux supports 3 system calls for controlling memory policy. These APIS
+Linux supports 4 system calls for controlling memory policy. These APIS
always affect only the calling task, the calling task's address space, or
some shared object mapped into the calling task's address space.
@@ -453,6 +460,20 @@ requested via the 'flags' argument.
See the mbind(2) man page for more details.
+Set home node for a Range of Task's Address Spacec::
+
+ long sys_set_mempolicy_home_node(unsigned long start, unsigned long len,
+ unsigned long home_node,
+ unsigned long flags);
+
+sys_set_mempolicy_home_node set the home node for a VMA policy present in the
+task's address range. The system call updates the home node only for the existing
+mempolicy range. Other address ranges are ignored. A home node is the NUMA node
+closest to which page allocation will come from. Specifying the home node override
+the default allocation policy to allocate memory close to the local node for an
+executing CPU.
+
+
Memory Policy Command Line Interface
====================================