From b084721752f93a3077df5b2d12ec3124f82dbc73 Mon Sep 17 00:00:00 2001 From: Michal Sekletar Date: Wed, 13 May 2026 16:20:55 +0200 Subject: [PATCH] core: make manager event loop rate limit configurable Co-developed-by: Claude Opus 4.6 (cherry picked from commit e1c63fd4c0657a7fc7b749c64283ab4dbc6fb39e) Resolves: RHEL-161564 --- man/org.freedesktop.systemd1.xml | 14 ++++++++++++++ man/systemd-system.conf.xml | 17 +++++++++++++++++ src/core/dbus-manager.c | 2 ++ src/core/main.c | 32 ++++++++++++++++++++++++++++++++ src/core/manager-serialize.c | 3 +++ src/core/manager.c | 3 +-- src/core/manager.h | 2 ++ src/core/system.conf.in | 2 ++ src/core/user.conf.in | 4 +++- 9 files changed, 76 insertions(+), 3 deletions(-) diff --git a/man/org.freedesktop.systemd1.xml b/man/org.freedesktop.systemd1.xml index 0b6be4c755..cc50db7f77 100644 --- a/man/org.freedesktop.systemd1.xml +++ b/man/org.freedesktop.systemd1.xml @@ -476,6 +476,10 @@ node /org/freedesktop/systemd1 { @org.freedesktop.DBus.Property.EmitsChangedSignal("const") readonly b DefaultBlockIOAccounting = ...; @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly t EventLoopRateLimitIntervalUSec = ...; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly u EventLoopRateLimitBurst = ...; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") readonly b DefaultIOAccounting = ...; @org.freedesktop.DBus.Property.EmitsChangedSignal("const") readonly b DefaultIPAccounting = ...; @@ -718,6 +722,10 @@ node /org/freedesktop/systemd1 { + + + + @@ -1164,6 +1172,10 @@ node /org/freedesktop/systemd1 { + + + + @@ -12241,6 +12253,8 @@ $ gdbus introspect --system --dest org.freedesktop.systemd1 \ ShutdownStartTimestamp, ShutdownStartTimestampMonotonic, and SoftRebootsCount were added in version 256. + EventLoopRateLimitIntervalUSec, and + EventLoopRateLimitBurst were added in version 261. Unit Objects diff --git a/man/systemd-system.conf.xml b/man/systemd-system.conf.xml index 23d09cfb37..1c71e54457 100644 --- a/man/systemd-system.conf.xml +++ b/man/systemd-system.conf.xml @@ -625,6 +625,23 @@ + + + EventLoopRateLimitIntervalSec= + EventLoopRateLimitBurst= + + Configures the rate limiting applied to the manager's main event loop. If the event + loop iterates more than EventLoopRateLimitBurst= times within + EventLoopRateLimitIntervalSec=, event processing is briefly paused to prevent + excessive CPU usage. EventLoopRateLimitIntervalSec= defaults to 1s. + EventLoopRateLimitBurst= defaults to 50000. These settings can also be set on the + kernel command line via + systemd.event_loop_ratelimit_interval_sec= and + systemd.event_loop_ratelimit_burst=. + + + + diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c index d516f30c96..3be3a536fe 100644 --- a/src/core/dbus-manager.c +++ b/src/core/dbus-manager.c @@ -3144,6 +3144,8 @@ const sd_bus_vtable bus_manager_vtable[] = { SD_BUS_PROPERTY("DefaultStartLimitBurst", "u", bus_property_get_unsigned, offsetof(Manager, defaults.start_limit.burst), SD_BUS_VTABLE_PROPERTY_CONST), SD_BUS_PROPERTY("DefaultCPUAccounting", "b", bus_property_get_bool, offsetof(Manager, defaults.cpu_accounting), SD_BUS_VTABLE_PROPERTY_CONST), SD_BUS_PROPERTY("DefaultBlockIOAccounting", "b", bus_property_get_bool, offsetof(Manager, defaults.blockio_accounting), SD_BUS_VTABLE_PROPERTY_CONST), + SD_BUS_PROPERTY("EventLoopRateLimitIntervalUSec", "t", bus_property_get_usec, offsetof(Manager, event_loop_ratelimit.interval), SD_BUS_VTABLE_PROPERTY_CONST), + SD_BUS_PROPERTY("EventLoopRateLimitBurst", "u", bus_property_get_unsigned, offsetof(Manager, event_loop_ratelimit.burst), SD_BUS_VTABLE_PROPERTY_CONST), SD_BUS_PROPERTY("DefaultIOAccounting", "b", bus_property_get_bool, offsetof(Manager, defaults.io_accounting), SD_BUS_VTABLE_PROPERTY_CONST), SD_BUS_PROPERTY("DefaultIPAccounting", "b", bus_property_get_bool, offsetof(Manager, defaults.ip_accounting), SD_BUS_VTABLE_PROPERTY_CONST), SD_BUS_PROPERTY("DefaultMemoryAccounting", "b", bus_property_get_bool, offsetof(Manager, defaults.memory_accounting), SD_BUS_VTABLE_PROPERTY_CONST), diff --git a/src/core/main.c b/src/core/main.c index 506bc00f1d..971ad50b7e 100644 --- a/src/core/main.c +++ b/src/core/main.c @@ -160,6 +160,8 @@ static void *arg_random_seed; static size_t arg_random_seed_size; static usec_t arg_reload_limit_interval_sec; static unsigned arg_reload_limit_burst; +static usec_t arg_event_loop_ratelimit_interval_sec; +static unsigned arg_event_loop_ratelimit_burst; /* A copy of the original environment block */ static char **saved_env = NULL; @@ -569,6 +571,28 @@ static int parse_proc_cmdline_item(const char *key, const char *value, void *dat return 0; } + } else if (proc_cmdline_key_streq(key, "systemd.event_loop_ratelimit_interval_sec")) { + + if (proc_cmdline_value_missing(key, value)) + return 0; + + r = parse_sec(value, &arg_event_loop_ratelimit_interval_sec); + if (r < 0) { + log_warning_errno(r, "Failed to parse systemd.event_loop_ratelimit_interval_sec= argument '%s', ignoring: %m", value); + return 0; + } + + } else if (proc_cmdline_key_streq(key, "systemd.event_loop_ratelimit_burst")) { + + if (proc_cmdline_value_missing(key, value)) + return 0; + + r = safe_atou(value, &arg_event_loop_ratelimit_burst); + if (r < 0) { + log_warning_errno(r, "Failed to parse systemd.event_loop_ratelimit_burst= argument '%s', ignoring: %m", value); + return 0; + } + } else if (streq(key, "quiet") && !value) { if (arg_show_status == _SHOW_STATUS_INVALID) @@ -833,6 +857,8 @@ static int parse_config_file(void) { { "Manager", "DefaultOOMScoreAdjust", config_parse_oom_score_adjust, 0, NULL }, { "Manager", "ReloadLimitIntervalSec", config_parse_sec, 0, &arg_reload_limit_interval_sec }, { "Manager", "ReloadLimitBurst", config_parse_unsigned, 0, &arg_reload_limit_burst }, + { "Manager", "EventLoopRateLimitIntervalSec", config_parse_sec, 0, &arg_event_loop_ratelimit_interval_sec }, + { "Manager", "EventLoopRateLimitBurst", config_parse_unsigned, 0, &arg_event_loop_ratelimit_burst }, #if ENABLE_SMACK { "Manager", "DefaultSmackProcessLabel", config_parse_string, 0, &arg_defaults.smack_process_label }, #else @@ -918,6 +944,8 @@ static void set_manager_settings(Manager *m) { * counter on every daemon-reload. */ m->reload_reexec_ratelimit.interval = arg_reload_limit_interval_sec; m->reload_reexec_ratelimit.burst = arg_reload_limit_burst; + m->event_loop_ratelimit.interval = arg_event_loop_ratelimit_interval_sec; + m->event_loop_ratelimit.burst = arg_event_loop_ratelimit_burst; manager_set_watchdog(m, WATCHDOG_RUNTIME, arg_runtime_watchdog); manager_set_watchdog(m, WATCHDOG_REBOOT, arg_reboot_watchdog); @@ -2776,6 +2804,10 @@ static void reset_arguments(void) { arg_reload_limit_interval_sec = 0; arg_reload_limit_burst = 0; + + arg_event_loop_ratelimit_interval_sec = 1 * USEC_PER_SEC; + arg_event_loop_ratelimit_burst = 50000; + } static void determine_default_oom_score_adjust(void) { diff --git a/src/core/manager-serialize.c b/src/core/manager-serialize.c index b225799ed9..a0923b2203 100644 --- a/src/core/manager-serialize.c +++ b/src/core/manager-serialize.c @@ -157,6 +157,7 @@ int manager_serialize( (void) serialize_ratelimit(f, "dump-ratelimit", &m->dump_ratelimit); (void) serialize_ratelimit(f, "reload-reexec-ratelimit", &m->reload_reexec_ratelimit); + (void) serialize_ratelimit(f, "event-loop-ratelimit", &m->event_loop_ratelimit); (void) serialize_id128(f, "bus-id", m->bus_id); bus_track_serialize(m->subscribed, f, "subscribed"); @@ -523,6 +524,8 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) { deserialize_ratelimit(&m->dump_ratelimit, "dump-ratelimit", val); else if ((val = startswith(l, "reload-reexec-ratelimit="))) deserialize_ratelimit(&m->reload_reexec_ratelimit, "reload-reexec-ratelimit", val); + else if ((val = startswith(l, "event-loop-ratelimit="))) + deserialize_ratelimit(&m->event_loop_ratelimit, "event-loop-ratelimit", val); else if ((val = startswith(l, "soft-reboots-count="))) { unsigned n; diff --git a/src/core/manager.c b/src/core/manager.c index 22efab33df..ef17f873b4 100644 --- a/src/core/manager.c +++ b/src/core/manager.c @@ -3412,7 +3412,6 @@ static int manager_dispatch_jobs_in_progress(sd_event_source *source, usec_t use } int manager_loop(Manager *m) { - RateLimit rl = { .interval = 1*USEC_PER_SEC, .burst = 50000 }; int r; assert(m); @@ -3429,7 +3428,7 @@ int manager_loop(Manager *m) { (void) watchdog_ping(); - if (!ratelimit_below(&rl)) { + if (!ratelimit_below(&m->event_loop_ratelimit)) { /* Yay, something is going seriously wrong, pause a little */ log_warning("Looping too fast. Throttling execution a little."); sleep(1); diff --git a/src/core/manager.h b/src/core/manager.h index 66ad04baf5..63726f70ab 100644 --- a/src/core/manager.h +++ b/src/core/manager.h @@ -504,6 +504,8 @@ struct Manager { RateLimit dump_ratelimit; sd_event_source *memory_pressure_event_source; + /* Rate limit for the manager event loop */ + RateLimit event_loop_ratelimit; /* For NFTSet= */ FirewallContext *fw_ctx; diff --git a/src/core/system.conf.in b/src/core/system.conf.in index 4fe420c344..f095d5bf8e 100644 --- a/src/core/system.conf.in +++ b/src/core/system.conf.in @@ -82,3 +82,5 @@ #DefaultSmackProcessLabel= #ReloadLimitIntervalSec= #ReloadLimitBurst= +#EventLoopRateLimitIntervalSec=1s +#EventLoopRateLimitBurst=50000 diff --git a/src/core/user.conf.in b/src/core/user.conf.in index 14f0eae7f8..fa81824c65 100644 --- a/src/core/user.conf.in +++ b/src/core/user.conf.in @@ -56,4 +56,6 @@ #DefaultMemoryPressureWatch=auto #DefaultSmackProcessLabel= #ReloadLimitIntervalSec= -#ReloadLimitBurst +#ReloadLimitBurst= +#EventLoopRateLimitIntervalSec=1s +#EventLoopRateLimitBurst=50000