nohang.conf

    This is nohang config file.
    Lines starting with #, tabs and spaces are comments.
    Lines starting with @ contain optional parameters.

    The configuration includes the following sections:

    1. Memory levels to respond to as an OOM threat
    2. Response on PSI memory metrics
    3. The frequency of checking the level of available memory
       (and CPU usage)
    4. The prevention of killing innocent victims
    5. Impact on the badness of processes via matching their
        - names,
        - cgroups,
        - cmdlines and
        - UIDs
        with regular expressions
    6. Customize corrective actions: the execution of a specific command
       instead of sending the SIGTERM signal
    7. GUI notifications:
       - OOM prevention results and
       - low memory warnings
    8. Output verbosity
    9. Misc

    Just read the description of the parameters and edit the values.
    Please restart the program after editing the config.

    Bool values are case sensitive.

#####################################################################

    1. Thresholds below which a signal should be sent to the victim

    Sets the available memory levels at or below which SIGTERM or SIGKILL
    signals are sent. The signal will be sent if MemAvailable and
    SwapFree (in /proc/meminfo) at the same time will drop below the
    corresponding values. Can be specified in % (percent) and M (MiB).
    Valid values are floating-point numbers from the range [0; 100] %.

    MemAvailable levels.

mem_min_sigterm = 10 %
mem_min_sigkill =  5 %

    SwapFree levels.

swap_min_sigterm = 15 %
swap_min_sigkill =  5 %

    Specifying the total share of zram in memory, if exceeded the
    corresponding signals are sent. As the share of zram in memory
    increases, it may fall responsiveness of the system. 90 % is a
    usual hang level, not recommended to set very high.

    Can be specified in % and M. Valid values are floating-point
    numbers from the range [0; 90] %.

zram_max_sigterm = 50 %
zram_max_sigkill = 55 %

#####################################################################

    2. Response on PSI memory metrics (it needs Linux 4.20 and up)

    About PSI:
    https://facebookmicrosites.github.io/psi/

    Disabled by default (ignore_psi = True).

ignore_psi = True

    Choose a path to PSI file.
    By default it monitors system-wide file: /proc/pressure/memory
    You also can set file to monitor one cgroup slice.
    For example:
    psi_path = /sys/fs/cgroup/unified/user.slice/memory.pressure
    psi_path = /sys/fs/cgroup/unified/system.slice/memory.pressure
    psi_path = /sys/fs/cgroup/unified/system.slice/foo.service/memory.pressure

    Execute the command
    find /sys/fs/cgroup -name memory.pressure
    to find available memory.pressue files (except /proc/pressure/memory).
    (actual for cgroup2)

psi_path = /proc/pressure/memory

    Valid psi_metrics are:
    some_avg10
    some_avg60
    some_avg300
    full_avg10
    full_avg60
    full_avg300

    some_avg10 is most sensitive.

psi_metrics = some_avg10

sigterm_psi_threshold = 80
sigkill_psi_threshold = 90

psi_post_action_delay = 60

#####################################################################

    3. The frequency of checking the amount of available memory
       (and CPU usage)

    Coefficients that affect the intensity of monitoring. Reducing
    the coefficients can reduce CPU usage and increase the periods
    between memory checks.

    Why three coefficients instead of one? Because the swap fill rate
    is usually lower than the RAM fill rate.

    It is possible to set a lower intensity of monitoring for swap
    without compromising to prevent OOM and thus reduce the CPU load.

    Default values are well for desktop. On servers without rapid
    fluctuations in memory levels the values can be reduced.

    Valid values are positive floating-point numbers.

rate_mem  = 4000
rate_swap = 1500
rate_zram =  500

    See also https://github.com/rfjakob/earlyoom/issues/61

max_sleep_time = 3

min_sleep_time = 0.1

#####################################################################

    4. The prevention of killing innocent victims

    Valid values are integers from the range [0; 1000].

min_badness = 20

    Valid values are non-negative floating-point numbers.

min_delay_after_sigterm = 0.2
min_delay_after_sigkill = 1

    Valid values are True and False.
    Values are case sensitive.

decrease_oom_score_adj = False

    Valid values are integers from the range [0; 1000].

oom_score_adj_max = 20

#####################################################################

    5. Impact on the badness of processes via matching their names,
       cmdlines or UIDs with regular expressions using re.search().

    See https://en.wikipedia.org/wiki/Regular_expression and
    https://en.wikipedia.org/wiki/Perl_Compatible_Regular_Expressions

    Enabling this options slows down the search for the victim
    because the names, cmdlines or UIDs of all processes
    (except init and kthreads) are compared with the
    specified regex patterns (in fact slowing down is caused by
    reading all /proc/*/cmdline and /proc/*/status files).

    Use script `oom-sort` from nohang package to view
    names, cmdlines and UIDs of processes.


    5.1 Matching process names with RE patterns

    Syntax:

    @PROCESSNAME_RE badness_adj /// RE_pattern

    New badness value will be += badness_adj

    It is possible to compare multiple patterns
    with different badness_adj values.

    Example:

    @PROCESSNAME_RE -500 /// ^sshd$

    5.2 Matching cmdlines with RE patterns

    A good option that allows fine adjustment.

    @CMDLINE_RE  300 /// -childID|--type=renderer

    @CMDLINE_RE -200 /// ^/usr/lib/virtualbox

    5.3 Matching UIDs with RE patterns

    The most slow option

    @UID_RE -100 /// ^0$

    5.4 Matching CGroup-line with RE patterns

    @CGROUP_V1_RE -50 /// ^/system.slice

    @CGROUP_V1_RE  50 /// foo.service

    @CGROUP_V1_RE -50 /// ^/user.slice

    @CGROUP_V2_RE  100 /// ^/workload

    5.5 Matching realpath with RE patterns

    @REALPATH_RE 20 /// ^/usr/bin/foo

    5.6 Matching environ with RE patterns

    @ENVIRON_RE 100 /// USER=user

    Note that you can control badness also via systemd units via OOMScoreAdjust, see
    https://www.freedesktop.org/software/systemd/man/systemd.exec.html#OOMScoreAdjust=

#####################################################################

    6. Customize corrective actions.

    TODO: docs

    Syntax:
    KEY                         REGEXP    SEPARATOR     COMMAND

    @SOFT_ACTION_RE_NAME         ^foo$     ///         kill -SEGV $PID
    @SOFT_ACTION_RE_NAME         ^bash$    ///         kill -9 $PID

    @SOFT_ACTION_RE_CGROUP_V1  ^/system.slice/  ///     systemctl restart $SERVICE
    @SOFT_ACTION_RE_CGROUP_V1  foo.service$     ///     systemctl restart $SERVICE

    $PID will be replaced by process PID.
    $NAME will be replaced by process name.
    $SERVICE will be replaced by .service if it exists (overwise it will be relpaced by empty line).

#####################################################################

    7. GUI notifications:
       - OOM prevention results and
       - low memory warnings

gui_notifications = False

    Enable GUI notifications about the low level of available memory.
    Valid values are True and False.

gui_low_memory_warnings = False

    Execute the command instead of sending GUI notifications if the value is
    not empty line. For example:
    warning_exe = cat /proc/meminfo &

warning_exe =

    Can be specified in % (percent) and M (MiB).
    Valid values are floating-point numbers from the range [0; 100] %.

mem_min_warnings = 25 %

swap_min_warnings = 50 %

zram_max_warnings = 40 %

    Valid values are floating-point numbers from the range [1; 300].

min_time_between_warnings = 15

    Ampersands (&) will be replaced with asterisks (*) in process
    names and in commands.

#####################################################################

    8. Verbosity

    Display the configuration when the program starts.
    Valid values are True and False.

print_config = False

    Print memory check results.
    Valid values are True and False.

print_mem_check_results = False

min_mem_report_interval = 60

    Print sleep periods between memory checks.
    Valid values are True and False.

print_sleep_periods = False

print_total_stat = True

print_proc_table = True

    Valid values:
    None
    cgroup_v1
    cgroup_v2
    cmdline
    environ
    realpath
    All

extra_table_info = cgroup_v1

print_victim_info = True

max_ancestry_depth = 1

separate_log = False

psi_debug = False

#####################################################################

    9. Misc

max_post_sigterm_victim_lifetime = 10

post_kill_exe =

forbid_negative_badness = True