From: xu xin <xu.xin16@xxxxxxxxxx> The following patch series bring a NEW running state "auto mode". In traditional KSM, whether ksmd works scanning and merging or not depends on the sysfs klob ksm_run. Most of time, letting ksmd run is not very much needed, for example, when memory is sufficient, because it increases the delays of COW for user applications and also consume extra cpu resource. Besides, the fixed pages_to_scan is not always good. When there are a lot of same pages, the default pages_to_scan makes ksmd so slow to merge them. The four patches try to optimize the above two points with a auto mode. It's a lightweight optimization to KSM, not like uksm or pksm and so on. The tests show: The convergence time of merging time of auto-mode reduces can low to HALF of normal-mode. The cpu consumption of auto-mode also get less than normal-mode. There are two type of TEST which have different shape of samepage areas. One is full-samepages vm areas, and the other is sparse-samepage areas. Both of the madvise area'size are 300MB. Here is test log: ****************** TEST 1 ****************** Now the shape of memory area is full-samepages: [xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx] Start to test normal-run ksmd... ksm current cpu total slice: 15274 ksm normal-run's merging time: 45.596018 seconds ksm current cpu total slice: 16370 Start to test auto-run ksmd... ksm auto-run's merging time: 17.599391 seconds ksm current cpu total slice: 16488 ****************** TEST 2 ****************** Now the shape of memory area is sparse-samepages: [xx] [xx] [xx] Start to test normal-run ksmd... ksm current cpu total slice: 16532 ksm normal-run's merging time: 21.625451 seconds ksm current cpu total slice: 16833 Start to test auto-run ksmd... ksm auto-run's merging time: 17.684379 seconds ksm current cpu total slice: 16950 Change log ========== for v2: 1. We adjust the scan-enhanced algorithm, abstract its implementation into a single function, which is clearer and smoother. 2. Add tests of auto-mode of ksm to verify the effectiveness. xu xin (5): ksm: add a auto-run mode of ksm ksm: implement scan-enhanced algorithm ksm: let ksmd auto-work with memory threshold ksm: show ksmd status for auto mode ksm: add tests of ksm auto mode mm/ksm.c | 250 ++++++++++++++++++- tools/testing/selftests/vm/.gitignore | 1 + tools/testing/selftests/vm/Makefile | 1 + tools/testing/selftests/vm/test-ksm-auto.c | 273 +++++++++++++++++++++ 4 files changed, 519 insertions(+), 6 deletions(-) create mode 100644 tools/testing/selftests/vm/test-ksm-auto.c -- 2.25.1
