Files
linux/tools/testing/selftests
Konstantin Khlebnikov 0085d61fe0 selftests/vm/transhuge-stress: stress test for memory compaction
This tool induces memory fragmentation via sequential allocation of
transparent huge pages and splitting off everything except their last
sub-pages.  It easily generates pressure to the memory compaction code.

$ perf stat -e 'compaction:*' -e 'migrate:*' ./transhuge-stress
transhuge-stress: allocate 7858 transhuge pages, using 15716 MiB virtual memory and 61 MiB of ram
transhuge-stress: 1.653 s/loop, 0.210 ms/page,   9504.828 MiB/s	7858 succeed,    0 failed, 2439 different pages
transhuge-stress: 1.537 s/loop, 0.196 ms/page,  10226.227 MiB/s	7858 succeed,    0 failed, 2364 different pages
transhuge-stress: 1.658 s/loop, 0.211 ms/page,   9479.215 MiB/s	7858 succeed,    0 failed, 2179 different pages
transhuge-stress: 1.617 s/loop, 0.206 ms/page,   9716.992 MiB/s	7858 succeed,    0 failed, 2421 different pages
^C./transhuge-stress: Interrupt

 Performance counter stats for './transhuge-stress':

         1.744.051      compaction:mm_compaction_isolate_migratepages
             1.014      compaction:mm_compaction_isolate_freepages
         1.744.051      compaction:mm_compaction_migratepages
             1.647      compaction:mm_compaction_begin
             1.647      compaction:mm_compaction_end
         1.744.051      migrate:mm_migrate_pages
                 0      migrate:mm_numa_migrate_ratelimit

       7,964696835 seconds time elapsed

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:26:01 -04:00
..
2014-05-12 00:23:55 -04:00

Linux Kernel Selftests

The kernel contains a set of "self tests" under the tools/testing/selftests/
directory. These are intended to be small unit tests to exercise individual
code paths in the kernel.

On some systems, hot-plug tests could hang forever waiting for cpu and
memory to be ready to be offlined. A special hot-plug target is created
to run full range of hot-plug tests. In default mode, hot-plug tests run
in safe mode with a limited scope. In limited mode, cpu-hotplug test is
run on a single cpu as opposed to all hotplug capable cpus, and memory
hotplug test is run on 2% of hotplug capable memory instead of 10%.

Running the selftests (hotplug tests are run in limited mode)
=============================================================

To build the tests:

  $ make -C tools/testing/selftests


To run the tests:

  $ make -C tools/testing/selftests run_tests

- note that some tests will require root privileges.

To run only tests targeted for a single subsystem: (including
hotplug targets in limited mode)

  $  make -C tools/testing/selftests TARGETS=cpu-hotplug run_tests

See the top-level tools/testing/selftests/Makefile for the list of all possible
targets.

Running the full range hotplug selftests
========================================

To build the tests:

  $ make -C tools/testing/selftests hotplug

To run the tests:

  $ make -C tools/testing/selftests run_hotplug

- note that some tests will require root privileges.

Contributing new tests
======================

In general, the rules for for selftests are

 * Do as much as you can if you're not root;

 * Don't take too long;

 * Don't break the build on any architecture, and

 * Don't cause the top-level "make run_tests" to fail if your feature is
   unconfigured.