On Wed, Jun 23, 2021 at 12:28 PM Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > > In modern systems it's not unusual to have a system component monitoring > memory conditions of the system and tasked with keeping system memory > pressure under control. One way to accomplish that is to kill > non-essential processes to free up memory for more important ones. > Examples of this are Facebook's OOM killer daemon called oomd and > Android's low memory killer daemon called lmkd. > For such system component it's important to be able to free memory > quickly and efficiently. Unfortunately the time process takes to free > up its memory after receiving a SIGKILL might vary based on the state > of the process (uninterruptible sleep), size and OPP level of the core > the process is running. A mechanism to free resources of the target > process in a more predictable way would improve system's ability to > control its memory pressure. > Introduce process_reap system call that reclaims memory of a dying process > from the context of the caller. This way the memory in freed in a more > controllable way with CPU affinity and priority of the caller. The workload > of freeing the memory will also be charged to the caller. > The operation is allowed only on a dying process. At the risk of asking a potentially silly question, should this just be a file in procfs? Also, please consider removing all mention of the word "reap" from the user API. For better or for worse, "reap" in UNIX refers to what happens when a dead task gets wait()ed. I sincerely wish I could go back in time and gently encourage whomever invented that particular abomination to change their mind, but my time machine doesn't work. --Andy
