The main reasons for the prolonged exit of a background process is the time-consuming release of its swap entries. The proportion of swap memory occupied by the background process increases with its duration in the background, and after a period of time, this value can reach 60% or more. Additionally, the relatively lengthy path for releasing swap entries further contributes to the longer time required for the background process to release its swap entries. In the multiple background applications scenario, when launching a large memory application such as a camera, system may enter a low memory state, which will triggers the killing of multiple background processes at the same time. Due to multiple exiting processes occupying multiple CPUs for concurrent execution, the current foreground application's CPU resources are tight and may cause issues such as lagging. To solve this problem, we have introduced the multiple exiting process asynchronous swap memory release mechanism, which isolates and caches swap entries occupied by multiple exit processes, and hands them over to an asynchronous kworker to complete the release. This allows the exiting processes to complete quickly and release CPU resources. We have validated this modification on the products and achieved the expected benefits. It offers several benefits: 1. Alleviate the high system cpu load caused by multiple exiting processes running simultaneously. 2. Reduce lock competition in swap entry free path by an asynchronous kworker instead of multiple exiting processes parallel execution. 3. Release memory occupied by exiting processes more efficiently. -v2: 1. fix arch s390 config compilation warning. Reported-by: kernel test robot <lkp@xxxxxxxxx> Closes: https://lore.kernel.org/oe-kbuild-all/202407311703.8q8sDQ2p-lkp@xxxxxxxxx/ Reported-by: kernel test robot <lkp@xxxxxxxxx> Closes: https://lore.kernel.org/oe-kbuild-all/202407311947.VPJNRqad-lkp@xxxxxxxxx/ -v1: https://lore.kernel.org/linux-mm/20240730114426.511-1-justinjiang@xxxxxxxx/ Zhiguo Jiang (3): mm: move task_is_dying to h headfile mm: tlb: add tlb swap entries batch async release mm: s390: fix compilation warning arch/s390/include/asm/tlb.h | 8 + include/asm-generic/tlb.h | 44 ++++++ include/linux/mm_types.h | 58 +++++++ include/linux/oom.h | 6 + mm/memcontrol.c | 6 - mm/memory.c | 3 +- mm/mmu_gather.c | 297 ++++++++++++++++++++++++++++++++++++ 7 files changed, 415 insertions(+), 7 deletions(-) -- 2.39.0
