X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=Documentation%2Fcpusets.txt;h=ec9de6917f01f34c088cd612121caaadc3edf08b;hb=fc8a327db6c46de783b1a4276d846841b9abc24c;hp=76b44290c1546c50a4e15527c18a19e626249f35;hpb=0a7d5f8ce960e74fa22986bda4af488539796e49;p=karo-tx-linux.git

diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt
index 76b44290c154..ec9de6917f01 100644
--- a/Documentation/cpusets.txt
+++ b/Documentation/cpusets.txt
@@ -35,7 +35,8 @@ CONTENTS:
 ----------------------
 
 Cpusets provide a mechanism for assigning a set of CPUs and Memory
-Nodes to a set of tasks.
+Nodes to a set of tasks.   In this document "Memory Node" refers to
+an on-line node that contains memory.
 
 Cpusets constrain the CPU and Memory placement of tasks to only
 the resources within a tasks current cpuset.  They form a nested
@@ -86,9 +87,6 @@ This can be especially valuable on:
       and a database), or
     * NUMA systems running large HPC applications with demanding
       performance characteristics.
-    * Also cpu_exclusive cpusets are useful for servers running orthogonal
-      workloads such as RT applications requiring low latency and HPC
-      applications that are throughput sensitive
 
 These subsets, or "soft partitions" must be able to be dynamically
 adjusted, as the job mix changes, without impacting other concurrently
@@ -131,8 +129,6 @@ Cpusets extends these two mechanisms as follows:
  - A cpuset may be marked exclusive, which ensures that no other
    cpuset (except direct ancestors and descendents) may contain
    any overlapping CPUs or Memory Nodes.
-   Also a cpu_exclusive cpuset would be associated with a sched
-   domain.
  - You can list all the tasks (by pid) attached to any cpuset.
 
 The implementation of cpusets requires a few, simple hooks
@@ -144,9 +140,6 @@ into the rest of the kernel, none in performance critical paths:
    allowed in that tasks cpuset.
  - in sched.c migrate_all_tasks(), to keep migrating tasks within
    the CPUs allowed by their cpuset, if possible.
- - in sched.c, a new API partition_sched_domains for handling
-   sched domain changes associated with cpu_exclusive cpusets
-   and related changes in both sched.c and arch/ia64/kernel/domain.c
  - in the mbind and set_mempolicy system calls, to mask the requested
    Memory Nodes by what's allowed in that tasks cpuset.
  - in page_alloc.c, to restrict memory to allowed nodes.
@@ -217,11 +210,11 @@ exclusive cpuset.  Also, the use of a Linux virtual file system (vfs)
 to represent the cpuset hierarchy provides for a familiar permission
 and name space for cpusets, with a minimum of additional kernel code.
 
-The cpus file in the root (top_cpuset) cpuset is read-only.
-It automatically tracks the value of cpu_online_map, using a CPU
-hotplug notifier.  If and when memory nodes can be hotplugged,
-we expect to make the mems file in the root cpuset read-only
-as well, and have it track the value of node_online_map.
+The cpus and mems files in the root (top_cpuset) cpuset are
+read-only.  The cpus file automatically tracks the value of
+cpu_online_map using a CPU hotplug notifier, and the mems file
+automatically tracks the value of node_states[N_MEMORY]--i.e.,
+nodes with memory--using the cpuset_track_online_nodes() hook.
 
 
 1.4 What are exclusive cpusets ?
@@ -231,15 +224,6 @@ 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 cpu_exclusive has a scheduler (sched) domain
-associated with it.  The sched domain consists of all CPUs in the
-current cpuset that are not part of any exclusive child cpusets.
-This ensures that the scheduler load balancing code only balances
-against the CPUs that are in the sched domain as defined above and
-not all of the CPUs in the system. This removes any overhead due to
-load balancing code trying to pull tasks outside of the cpu_exclusive
-cpuset only to be prevented by the tasks' cpus_allowed mask.
-
 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
@@ -557,6 +541,9 @@ Set some flags:
 Add some cpus:
 # /bin/echo 0-7 > cpus
 
+Add some mems:
+# /bin/echo 0-7 > mems
+
 Now attach your shell to this cpuset:
 # /bin/echo $$ > tasks