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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>
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.