Messages in this thread | | | From | Zhaoyang Huang <> | Date | Tue, 10 Apr 2018 17:51:14 +0800 | Subject | Re: [PATCH v1] ringbuffer: Don't choose the process with adj equal OOM_SCORE_ADJ_MIN |
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On Tue, Apr 10, 2018 at 5:32 PM, Zhaoyang Huang <huangzhaoyang@gmail.com> wrote: > On Tue, Apr 10, 2018 at 5:01 PM, Michal Hocko <mhocko@kernel.org> wrote: >> On Tue 10-04-18 16:38:32, Zhaoyang Huang wrote: >>> On Tue, Apr 10, 2018 at 4:12 PM, Michal Hocko <mhocko@kernel.org> wrote: >>> > On Tue 10-04-18 16:04:40, Zhaoyang Huang wrote: >>> >> On Tue, Apr 10, 2018 at 3:49 PM, Michal Hocko <mhocko@kernel.org> wrote: >>> >> > On Tue 10-04-18 14:39:35, Zhaoyang Huang wrote: >>> >> >> On Tue, Apr 10, 2018 at 2:14 PM, Michal Hocko <mhocko@kernel.org> wrote: >>> > [...] >>> >> >> > OOM_SCORE_ADJ_MIN means "hide the process from the OOM killer completely". >>> >> >> > So what exactly do you want to achieve here? Because from the above it >>> >> >> > sounds like opposite things. /me confused... >>> >> >> > >>> >> >> Steve's patch intend to have the process be OOM's victim when it >>> >> >> over-allocating pages for ring buffer. I amend a patch over to protect >>> >> >> process with OOM_SCORE_ADJ_MIN from doing so. Because it will make >>> >> >> such process to be selected by current OOM's way of >>> >> >> selecting.(consider OOM_FLAG_ORIGIN first before the adj) >>> >> > >>> >> > I just wouldn't really care unless there is an existing and reasonable >>> >> > usecase for an application which updates the ring buffer size _and_ it >>> >> > is OOM disabled at the same time. >>> >> There is indeed such kind of test case on my android system, which is >>> >> known as CTS and Monkey etc. >>> > >>> > Does the test simulate a real workload? I mean we have two things here >>> > >>> > oom disabled task and an updater of the ftrace ring buffer to a >>> > potentially large size. The second can be completely isolated to a >>> > different context, no? So why do they run in the single user process >>> > context? >>> ok. I think there are some misunderstandings here. Let me try to >>> explain more by my poor English. There is just one thing here. The >>> updater is originally a oom disabled task with adj=OOM_SCORE_ADJ_MIN. >>> With Steven's patch, it will periodically become a oom killable task >>> by calling set_current_oom_origin() for user process which is >>> enlarging the ring buffer. What I am doing here is limit the user >>> process to the ones that adj > -1000. >> >> I've understood that part. And I am arguing whether this is really such >> an important case to play further tricks. Wouldn't it be much simpler to >> put the updater out to a separate process? OOM disabled processes >> shouldn't really do unexpectedly large allocations. Full stop. Otherwise >> you risk a large system disruptions. >> -- > It is a real problem(my android system just hung there while running > the test case for the innocent key process killed by OOM), however, > the problem is we can not define the userspace's behavior as you > suggested. What Steven's patch doing here is to keep the system to be > stable by having the updater to take the responsbility itself. My > patch is to let the OOM disabled processes remain the unkillable > status. > >> Michal Hocko >> SUSE Labs To summarize the patch sets as 'let the updater take the responsibility itself, don't harm to the innocent, but absolve the critical process'
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