https://fedoraproject.org/wiki/Changes/EnableEarlyoom == Summary == Install earlyoom package, and enable it by default. This will cause the kernel oomkiller to trigger sooner, but will not affect which process it chooses to kill off. The idea is to recover from out of memory situations sooner, rather than the typical complete system hang in which the user has no other choice but to force power off. == Owner == * Name: [[User:chrismurphy| Chris Murphy]] * Email: bugzilla(a)colorremedies.com == Detailed Description == Workstation working group has discussed "better interactivity in low-memory situations" for some months. In certain use cases, typically compiling, if all RAM and swap are completely consumed, system responsiveness becomes so abysmal that a reasonable user can consider the system "lost", and resorts to forcing a power off. This is objective a very bad UX. The broad discussion of this problem, and some ideas for near term and long term solutions, is located here: Recent long discussions on "Better interactivity in low-memory situations"<br> https://pagure.io/fedora-workstation/issue/98<br> https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.o... Fedora editions and spins, have the in-kernel OOM (out-of-memory) manager enabled. The manager's concern is keeping the kernel itself functioning. It has no concern about user space function or interactivity. This proposed change attempts to improve the user experience, in the short term, by triggering the in-kernel process killing mechanism, sooner. Instead of the system becoming completely unresponsive for tens of minutes, hours or days, the expectation is an offending process (determined by oom_score, same as now) will be killed off within seconds or a few minutes. This is an incremental improvement in user experience, but admittedly still suboptimal. There is additional work on-going to improve the user experience further. Workstation working group discussion specific to enabling earlyoom by default https://pagure.io/fedora-workstation/issue/119 Other in-progress solutions:<br> https://gitlab.freedesktop.org/hadess/low-memory-monitor<br> Background information on this complicated problem:<br> https://www.kernel.org/doc/gorman/html/understand/understand016.html<b... https://lwn.net/Articles/317814/<br> == Benefit to Fedora == There are two major benefits to Fedora: * improved user experience by more quickly regaining control over one's system, rather than having to force power off in low-memory situations where there's aggressive swapping. Once a system becomes unresponsive, it's completely reasonable for the user to assume the system is lost, but that includes high potential for data loss. * reducing forced poweroff as the main work around will increase data collection, improving understanding of low memory situations and how to handle them better == Scope == * Proposal owners: a. Modify {{code|https://pagure.io/fedora-comps/blob/master/f/comps-f32.xml.in}} to include earlyoom package for Workstation.<br> b. Modify {{code|https://src.fedoraproject.org/rpms/fedora-release/blob/master/f/80-workstation.preset}} to include: <pre> # enable earlyoom by default on workstation enable earlyoom.service </pre> * Other developers: Restricted to Workstation edition, unless other editions/spins want to opt-in. * Release engineering: [https://pagure.io/releng/issues #9141] (a check of an impact with Release Engineering is needed) <!-- REQUIRED FOR SYSTEM WIDE CHANGES --> * Policies and guidelines: N/A * Trademark approval: N/A == Upgrade/compatibility impact == earlyoom.service will be enabled on upgrade. An upgraded system should exhibit the same behaviors as a clean installed system. == How To Test == * Fedora 30/31 users can test today, any edition or spin:<br> {{code|sudo dnf install earlyoom}}<br> {{code|sudo systemctl enable --now earlyoom}} And then attempt to cause an out of memory situation. Examples:<br> {{code|tail /dev/zero}}<br> {{code|https://lkml.org/lkml/2019/8/4/15}} * Fedora Workstation 32 (and Rawhide) users will see this service is already enabled. It can be toggled with {{code|sudo systemctl start/stop earlyoom}} where start means earlyoom is running, and stop means earlyoom is not running. == User Experience == The most egregious instances this change is trying to mitigate: a. RAM is completely used b. Swap is completely used c. System becomes unresponsive to the user as swap thrashing has ensued --> earlyoom disabled, the user often gives up and forces power off (in my own testing this condition lasts >30 minutes with no kernel triggered oom killer and no recovery) --> earlyoom enabled, the system likely still becomes unresponsive but oom killer is triggered in much less time (seconds or a few minutes, in my testing, after less than 10% RAM and 10% swap is remaining) earlyoom starts sending SIGTERM once both memory and swap are below their respective PERCENT setting, default 10%. It sends SIGKILL once both are below their respective KILL_PERCENT setting, default 5%. The package includes configuration file /etc/default/earlyoom which sets option {{code|-r 60}} causing a memory report to be entered into the journal every minute. == Dependencies == earlyoom package has no dependencies == Contingency Plan == * Contingency mechanism: Owner will revert all changes * Contingency deadline: Final freeze * Blocks release? No * Blocks product? No == Documentation == {{code|man earlyoom}}<br><br> https://www.kernel.org/doc/gorman/html/understand/understand016.html == Release Notes == Earlyoom service is enabled by default, which will cause kernel oom-killer to trigger sooner. To revert to previous behavior:<br> {{code|sudo systemctl disable earlyoom.service}} And to customize see {{code|man earlyoom}}. -- Ben Cotton He / Him / His Fedora Program Manager Red Hat TZ=America/Indiana/Indianapolis