Beginning March 27, 2025, we advocate using android-newest-release as an alternative of aosp-important to build and contribute to AOSP. For more info, see Modifications to AOSP. Low memory killer daemon Keep organized with collections Save and categorize content material based mostly in your preferences. The Android low memory killer daemon (lmkd) course of screens the memory state of a working Android system and reacts to excessive memory strain by killing the least important processes to maintain the system performing at acceptable ranges. An Android system working multiple processes in parallel may encounter conditions when system memory is exhausted and processes that require extra memory experience noticeable delays. Memory pressure, a state during which the system is running short on memory, requires Android to free memory (to alleviate the strain) by throttling or killing unimportant processes, requesting processes to free noncritical cached resources, and so on. Historically, Android monitored system memory strain utilizing an in-kernel low memory killer (LMK) driver, a rigid mechanism that is dependent upon exhausting-coded values.

As of kernel 4.12, the LMK driver is removed from the upstream kernel and the userspace lmkd performs memory monitoring and process killing tasks. Android 10 and better support a new lmkd mode that makes use of kernel strain stall data (PSI) screens for memory pressure detection. The PSI patchset within the upstream kernel (backported to 4.9 and 4.14 kernels) measures the period of time that tasks are delayed as a result of memory shortages. As these delays directly affect user expertise, they characterize a convenient metric for determining memory strain severity. The upstream kernel also includes PSI screens that enable privileged userspace processes (akin to lmkd) to specify thresholds for these delays and to subscribe to occasions from the kernel when a threshold is breached. Because the vmpressure signals (generated by the kernel for Memory Wave strain detection and utilized by lmkd) often embrace numerous false positives, lmkd must perform filtering to determine if the memory is under real pressure.