On Mon, May 31, 2010 at 03:51:02PM +0900, KAMEZAWA Hiroyuki wrote: | On Mon, 31 May 2010 15:09:41 +0900 | Minchan Kim <minchan.kim@xxxxxxxxx> wrote: | > On Mon, May 31, 2010 at 2:54 PM, KAMEZAWA Hiroyuki | > <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: ... | > >> > IIUC, the purpose of rising priority is to accerate dying thread to exit() | > >> > for freeing memory AFAP. But to free memory, exit, all threads which share | > >> > mm_struct should exit, too. I'm sorry if I miss something. | > >> | > >> How do we kill only some thread and what's the benefit of it? | > >> I think when if some thread receives KILL signal, the process include | > >> the thread will be killed. | > >> | > > yes, so, if you want a _process_ die quickly, you have to acceralte the whole | > > threads on a process. Acceralating a thread in a process is not big help. | > | > Yes. | > | > I see the code. | > oom_kill_process is called by | > | > 1. mem_cgroup_out_of_memory | > 2. __out_of_memory | > 3. out_of_memory | > | > | > (1,2) calls select_bad_process which select victim task in processes | > by do_each_process. | > But 3 isn't In case of CONSTRAINT_MEMORY_POLICY, it kills current. | > In only the case, couldn't we pass task of process, not one of thread? | > | | Hmm, my point is that priority-acceralation is against a thread, not against a process. | So, most of threads in memory-eater will not gain high priority even with this patch | and works slowly. This is a good point... | I have no objections to this patch. I just want to confirm the purpose. If this patch | is for accelating exiting process by SIGKILL, it seems not enough. I understand (from the comments in the code) the badness calculation gives more points to the siblings in a thread that have their own mm. I wonder if what you are describing is not a corner case. Again, your idea sounds like an interesting refinement to the patch. I am just not sure this change should implemented now or in a second round of changes. | If an explanation as "acceralating all thread's priority in a process seems overkill" | is given in changelog or comment, it's ok to me. If my understanding of badness() is right, I wouldn't be ashamed of saying that it seems to be _a bit_ overkill. But I may be wrong in my interpretation. While re-reading the code I noticed that in select_bad_process() we can eventually bump on an already dying task, case in which we just wait for the task to die and avoid killing other tasks. Maybe we could boost the priority of the dying task here too. Luis -- [ Luis Claudio R. Goncalves Bass - Gospel - RT ] [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9 2696 7203 D980 A448 C8F8 ] -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>