On Tue, Mar 12, 2019 at 7:43 PM Tim Murray <timmurray@xxxxxxxxxx> wrote: > > On Tue, Mar 12, 2019 at 10:45 AM Sultan Alsawaf <sultan@xxxxxxxxxxxxxxx> wrote: > > > > On Tue, Mar 12, 2019 at 10:17:43AM -0700, Tim Murray wrote: > > > Knowing whether a SIGKILL'd process has finished reclaiming is as far > > > as I know not possible without something like procfds. That's where > > > the 100ms timeout in lmkd comes in. lowmemorykiller and lmkd both > > > attempt to wait up to 100ms for reclaim to finish by checking for the > > > continued existence of the thread that received the SIGKILL, but this > > > really means that they wait up to 100ms for the _thread_ to finish, > > > which doesn't tell you anything about the memory used by that process. > > > If those threads terminate early and lowmemorykiller/lmkd get a signal > > > to kill again, then there may be two processes competing for CPU time > > > to reclaim memory. That doesn't reclaim any faster and may be an > > > unnecessary kill. > > > ... > > > - offer a way to wait for process termination so lmkd can tell when > > > reclaim has finished and know when killing another process is > > > appropriate > > > > Should be pretty easy with something like this: > > Yeah, that's in the spirit of what I was suggesting, but there are lot > of edge cases around how to get that data out efficiently and PID > reuse (it's a real issue--often the Android apps that are causing > memory pressure are also constantly creating/destroying threads). > > I believe procfds or a similar mechanism will be a good solution to this. Fwiw, I am working on this and have send a PR for inclusion in 5.1: https://lore.kernel.org/lkml/20190312135245.27591-1-christian@xxxxxxxxxx/ There's also a tree to track this work. Christian
