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Bubberstation/code/__DEFINES/MC.dm
SkyratBot d8da1153b7 [MIRROR] Biddle Verbs: Queues the Most Expensive Verbs for the Next Tick if the Server Is Overloaded [MDB IGNORE] (#15329)
* Biddle Verbs: Queues the Most Expensive Verbs for the Next Tick if the Server Is Overloaded (#65589)

This pr goes through: /client/Click(), /client/Topic(), /mob/living/verb/resist(), /mob/verb/quick_equip(), /mob/verb/examinate(), and /mob/verb/mode() and makes them queue their functionality to a subsystem to execute in the next tick if the server is overloaded. To do this a new subsystem is made to handle most verbs called SSverb_manager, if the server is overloaded the verb queues itself in the subsystem and returns, then near the start of the next tick that verb is resumed with the provided callback. The verbs are called directly after SSinput, and the subsystem does not yield until its queue is completely finished.

The exception are clicks from player input since they are extremely important for the feeling of responsiveness. I considered not queuing them but theyre too expensive not to, suffering from a death of a thousand cuts performance wise from many many things in the process adding up. Instead clicks are executed at the very start of the next tick, as the first action that SSinput completes, before player movement is processed even.

A few months ago, before I died I was trying to figure out why games at midpop (40-50 people) had non zero and consistent time dilation without maptick being consistently above 28% (which is when the MC stops yielding for maptick if its overloaded). I found it out, started working on this pr, then promptly died. luckily im a bit less dead now

the current MC has a problem: the cost of verbs is completely and totally invisible to it, it cannot account for them. Why is this bad? because verbs are the last thing to execute in the tick, after the MC and SendMaps have finished executing.
tick diagram2
If the MC is overloaded and uses 100% of the time it allots itself this means that if SendMaps uses the amount its expected to take, verbs have at most 2% of the tick to execute in before they are overtiming and thus delaying the start of the next tick. This is bad, and im 99% sure this is the majority of our overtime.

Take Click() for example. Click isnt listed as a verb but since its called as a result of client commands its executed at the end of the tick like other verbs. in this random 80 pop sybil round profile i had saved on my computer sybil 80 pop (2).txt /client/Click() has an overtime of only 1.8 seconds, which isnt that bad. however it has a self cpu of 2.5 seconds meaning 1.8/2.5 = 72% of its time is overtiming, and it also is calling 80.2 seconds worth of total cpu, which means that more than 57.7 seconds of overtime is attributed to just /client/Click() executing at the very end of a tick. the reason why this isnt obvious is just because the verbs themselves typically dont have high enough self cpu to get high enough on the rankings of overtiming procs to be noticed, all of their overtime is distributed among a ton of procs they call in the chain.

Since i cant guarantee the MC resumes at the very start of the next tick due to other sleeping procs almost always resuming first: I time the duration between clicks being queued up for the next tick and when theyre actually executed. if it exceeds 20 milliseconds of added latency (less than one tenth the average human reaction time) clicks will execute immediately instead of queuing, this should make instances where a player can notice the added latency a vanishingly small minority of cases. still, this should be tm'd

* Biddle Verbs: Queues the Most Expensive Verbs for the Next Tick if the Server Is Overloaded

Co-authored-by: Kylerace <kylerlumpkin1@gmail.com>
2022-07-31 22:03:59 +00:00

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#define MC_TICK_CHECK ( ( TICK_USAGE > Master.current_ticklimit || src.state != SS_RUNNING ) ? pause() : 0 )
#define MC_SPLIT_TICK_INIT(phase_count) var/original_tick_limit = Master.current_ticklimit; var/split_tick_phases = ##phase_count
#define MC_SPLIT_TICK \
if(split_tick_phases > 1){\
Master.current_ticklimit = ((original_tick_limit - TICK_USAGE) / split_tick_phases) + TICK_USAGE;\
--split_tick_phases;\
} else {\
Master.current_ticklimit = original_tick_limit;\
}
// Used to smooth out costs to try and avoid oscillation.
#define MC_AVERAGE_FAST(average, current) (0.7 * (average) + 0.3 * (current))
#define MC_AVERAGE(average, current) (0.8 * (average) + 0.2 * (current))
#define MC_AVERAGE_SLOW(average, current) (0.9 * (average) + 0.1 * (current))
#define MC_AVG_FAST_UP_SLOW_DOWN(average, current) (average > current ? MC_AVERAGE_SLOW(average, current) : MC_AVERAGE_FAST(average, current))
#define MC_AVG_SLOW_UP_FAST_DOWN(average, current) (average < current ? MC_AVERAGE_SLOW(average, current) : MC_AVERAGE_FAST(average, current))
///creates a running average of "things elapsed" per time period when you need to count via a smaller time period.
///eg you want an average number of things happening per second but you measure the event every tick (50 milliseconds).
///make sure both time intervals are in the same units. doesnt work if current_duration > total_duration or if total_duration == 0
#define MC_AVG_OVER_TIME(average, current, total_duration, current_duration) (((total_duration - current_duration) / (total_duration)) * (average) + (current))
#define MC_AVG_MINUTES(average, current, current_duration) (MC_AVG_OVER_TIME(average, current, 1 MINUTES, current_duration))
#define MC_AVG_SECONDS(average, current, current_duration) (MC_AVG_OVER_TIME(average, current, 1 SECONDS, current_duration))
#define NEW_SS_GLOBAL(varname) if(varname != src){if(istype(varname)){Recover();qdel(varname);}varname = src;}
#define START_PROCESSING(Processor, Datum) if (!(Datum.datum_flags & DF_ISPROCESSING)) {Datum.datum_flags |= DF_ISPROCESSING;Processor.processing += Datum}
#define STOP_PROCESSING(Processor, Datum) Datum.datum_flags &= ~DF_ISPROCESSING;Processor.processing -= Datum;Processor.currentrun -= Datum
/// Returns true if the MC is initialized and running.
/// Optional argument init_stage controls what stage the mc must have initializted to count as initialized. Defaults to INITSTAGE_MAX if not specified.
#define MC_RUNNING(INIT_STAGE...) (Master && Master.processing > 0 && Master.current_runlevel && Master.init_stage_completed == (max(min(INITSTAGE_MAX, ##INIT_STAGE), 1)))
#define MC_LOOP_RTN_NEWSTAGES 1
#define MC_LOOP_RTN_GRACEFUL_EXIT 2
//! SubSystem flags (Please design any new flags so that the default is off, to make adding flags to subsystems easier)
/// subsystem does not initialize.
#define SS_NO_INIT 1
/** subsystem does not fire. */
/// (like can_fire = 0, but keeps it from getting added to the processing subsystems list)
/// (Requires a MC restart to change)
#define SS_NO_FIRE 2
/** Subsystem only runs on spare cpu (after all non-background subsystems have ran that tick) */
/// SS_BACKGROUND has its own priority bracket, this overrides SS_TICKER's priority bump
#define SS_BACKGROUND 4
/** Treat wait as a tick count, not DS, run every wait ticks. */
/// (also forces it to run first in the tick (unless SS_BACKGROUND))
/// (We don't want to be choked out by other subsystems queuing into us)
/// (implies all runlevels because of how it works)
/// This is designed for basically anything that works as a mini-mc (like SStimer)
#define SS_TICKER 8
/** keep the subsystem's timing on point by firing early if it fired late last fire because of lag */
/// ie: if a 20ds subsystem fires say 5 ds late due to lag or what not, its next fire would be in 15ds, not 20ds.
#define SS_KEEP_TIMING 16
/** Calculate its next fire after its fired. */
/// (IE: if a 5ds wait SS takes 2ds to run, its next fire should be 5ds away, not 3ds like it normally would be)
/// This flag overrides SS_KEEP_TIMING
#define SS_POST_FIRE_TIMING 32
//! SUBSYSTEM STATES
#define SS_IDLE 0 /// ain't doing shit.
#define SS_QUEUED 1 /// queued to run
#define SS_RUNNING 2 /// actively running
#define SS_PAUSED 3 /// paused by mc_tick_check
#define SS_SLEEPING 4 /// fire() slept.
#define SS_PAUSING 5 /// in the middle of pausing
// Subsystem init stages
#define INITSTAGE_EARLY 1 //! Early init stuff that doesn't need to wait for mapload
#define INITSTAGE_MAIN 2 //! Main init stage
#define INITSTAGE_MAX 2 //! Highest initstage.
#define SUBSYSTEM_DEF(X) GLOBAL_REAL(SS##X, /datum/controller/subsystem/##X);\
/datum/controller/subsystem/##X/New(){\
NEW_SS_GLOBAL(SS##X);\
PreInit();\
}\
/datum/controller/subsystem/##X
#define TIMER_SUBSYSTEM_DEF(X) GLOBAL_REAL(SS##X, /datum/controller/subsystem/timer/##X);\
/datum/controller/subsystem/timer/##X/New(){\
NEW_SS_GLOBAL(SS##X);\
PreInit();\
}\
/datum/controller/subsystem/timer/##X/fire() {..() /*just so it shows up on the profiler*/} \
/datum/controller/subsystem/timer/##X
#define MOVEMENT_SUBSYSTEM_DEF(X) GLOBAL_REAL(SS##X, /datum/controller/subsystem/movement/##X);\
/datum/controller/subsystem/movement/##X/New(){\
NEW_SS_GLOBAL(SS##X);\
PreInit();\
}\
/datum/controller/subsystem/movement/##X/fire() {..() /*just so it shows up on the profiler*/} \
/datum/controller/subsystem/movement/##X
#define PROCESSING_SUBSYSTEM_DEF(X) GLOBAL_REAL(SS##X, /datum/controller/subsystem/processing/##X);\
/datum/controller/subsystem/processing/##X/New(){\
NEW_SS_GLOBAL(SS##X);\
PreInit();\
}\
/datum/controller/subsystem/processing/##X/fire() {..() /*just so it shows up on the profiler*/} \
/datum/controller/subsystem/processing/##X
#define FLUID_SUBSYSTEM_DEF(X) GLOBAL_REAL(SS##X, /datum/controller/subsystem/fluids/##X);\
/datum/controller/subsystem/fluids/##X/New(){\
NEW_SS_GLOBAL(SS##X);\
PreInit();\
}\
/datum/controller/subsystem/fluids/##X/fire() {..() /*just so it shows up on the profiler*/} \
/datum/controller/subsystem/fluids/##X
#define VERB_MANAGER_SUBSYSTEM_DEF(X) GLOBAL_REAL(SS##X, /datum/controller/subsystem/verb_manager/##X);\
/datum/controller/subsystem/verb_manager/##X/New(){\
NEW_SS_GLOBAL(SS##X);\
PreInit();\
}\
/datum/controller/subsystem/verb_manager/##X/fire() {..() /*just so it shows up on the profiler*/} \
/datum/controller/subsystem/verb_manager/##X