The patch titled
x86_64: fake numa for cpusets document
has been added to the -mm tree. Its filename is
x86_64-fake-numa-for-cpusets-document.patch
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Subject: x86_64: fake numa for cpusets document
From: David Rientjes <rientjes@xxxxxxxxxx>
Create a document to explain how to use numa=fake in conjunction with cpusets
for coarse memory resource management.
An attempt to get more awareness and testing for this feature.
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Paul Jackson <pj@xxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/x86_64/fake-numa-for-cpusets | 66 +++++++++++++++++++
1 files changed, 66 insertions(+)
diff -puN /dev/null Documentation/x86_64/fake-numa-for-cpusets
--- /dev/null
+++ a/Documentation/x86_64/fake-numa-for-cpusets
@@ -0,0 +1,66 @@
+Using numa=fake and CPUSets for Resource Management
+Written by David Rientjes <rientjes@xxxxxxxxxxxxxxxxx>
+
+This document describes how the numa=fake x86_64 command-line option can be used
+in conjunction with cpusets for coarse memory management. Using this feature,
+you can create fake NUMA nodes that represent contiguous chunks of memory and
+assign them to cpusets and their attached tasks. This is a way of limiting the
+amount of system memory that are available to a certain class of tasks.
+
+For more information on the features of cpusets, see Documentation/cpusets.txt.
+There are a number of different configurations you can use for your needs. For
+more information on the numa=fake command line option and its various ways of
+configuring fake nodes, see Documentation/x86_64/boot-options.txt.
+
+For the purposes of this introduction, we'll assume a very primitive NUMA
+emulation setup of "numa=fake=4*512,". This will split our system memory into
+four equal chunks of 512M each that we can now use to assign to cpusets. As
+you become more familiar with using this combination for resource control,
+you'll determine a better setup to minimize the number of nodes you have to deal
+with.
+
+A machine may be split as follows with "numa=fake=4*512," as reported by dmesg:
+
+ Faking node 0 at 0000000000000000-0000000020000000 (512MB)
+ Faking node 1 at 0000000020000000-0000000040000000 (512MB)
+ Faking node 2 at 0000000040000000-0000000060000000 (512MB)
+ Faking node 3 at 0000000060000000-0000000080000000 (512MB)
+ ...
+ On node 0 totalpages: 130975
+ On node 1 totalpages: 131072
+ On node 2 totalpages: 131072
+ On node 3 totalpages: 131072
+
+Now following the instructions for mounting the cpusets filesystem from
+Documentation/cpusets.txt, you can assign fake nodes (i.e. contiguous memory
+address spaces) to individual cpusets:
+
+ [root@xroads /]# mkdir exampleset
+ [root@xroads /]# mount -t cpuset none exampleset
+ [root@xroads /]# mkdir exampleset/ddset
+ [root@xroads /]# cd exampleset/ddset
+ [root@xroads /exampleset/ddset]# echo 0-1 > cpus
+ [root@xroads /exampleset/ddset]# echo 0-1 > mems
+
+Now this cpuset, 'ddset', will only allowed access to fake nodes 0 and 1 for
+memory allocations (1G).
+
+You can now assign tasks to these cpusets to limit the memory resources
+available to them according to the fake nodes assigned as mems:
+
+ [root@xroads /exampleset/ddset]# echo $$ > tasks
+ [root@xroads /exampleset/ddset]# dd if=/dev/zero of=tmp bs=1024 count=1G
+ [1] 13425
+
+Notice the difference between the system memory usage as reported by
+/proc/meminfo between the restricted cpuset case above and the unrestricted
+case (i.e. running the same 'dd' command without assigning it to a fake NUMA
+cpuset):
+ Unrestricted Restricted
+ MemTotal: 3091900 kB 3091900 kB
+ MemFree: 42113 kB 1513236 kB
+
+This allows for coarse memory management for the tasks you assign to particular
+cpusets. Since cpusets can form a hierarchy, you can create some pretty
+interesting combinations of use-cases for various classes of tasks for your
+memory management needs.
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
x86_64-configurable-fake-numa-node-sizes.patch
x86_64-split-remaining-fake-nodes-equally.patch
x86_64-fixed-size-remaining-fake-nodes.patch
x86_64-map-fake-nodes-to-real-nodes.patch
x86_64-disable-alien-cache-for-fake-numa.patch
x86_64-export-physnode-mapping-to-userspace.patch
x86_64-fake-numa-for-cpusets-document.patch
smaps-extract-pmd-walker-from-smaps-code.patch
smaps-add-pages-referenced-count-to-smaps.patch
smaps-add-clear_refs-file-to-clear-reference.patch
smaps-add-clear_refs-file-to-clear-reference-fix.patch
smaps-add-clear_refs-file-to-clear-reference-fix-fix.patch
smaps-add-clear_refs-file-to-clear-reference-docs.patch
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