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chore: Encapsulate Admissions Control

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main
Sean McBride 4 years ago
parent 0eb699bb24
commit 067cbf6fc9
3 changed files with 123 additions and 118 deletions
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125
runtime/include/admissions_control.h
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#pragma once
#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <unistd.h>
#include "debuglog.h"
#include "client_socket.h"
#define ADMISSIONS_CONTROL_GRANULARITY 1000000
/*
* Unitless estimate of the instantaneous fraction of system capacity required to complete all previously
* admitted work. This is used to calculate free capacity as part of admissions control
*
* The estimated requirements of a single admitted request is calculated as
* estimated execution time (cycles) / relative deadline (cycles)
*
* These estimates are incremented on request acceptance and decremented on request completion (either
* success or failure)
*/
extern _Atomic uint64_t admissions_control_admitted;
extern uint64_t admissions_control_capacity;
extern const double admissions_control_overhead;
static inline void
admissions_control_initialize()
{
#ifdef ADMISSIONS_CONTROL
atomic_init(&admissions_control_admitted, 0);
admissions_control_capacity = runtime_worker_threads_count * ADMISSIONS_CONTROL_GRANULARITY
* ((double)1.0 - admissions_control_overhead);
#endif
}
static inline void
admissions_control_add(uint64_t admissions_estimate)
{
#ifdef ADMISSIONS_CONTROL
assert(admissions_estimate > 0);
atomic_fetch_add(&admissions_control_admitted, admissions_estimate);
#ifdef LOG_ADMISSIONS_CONTROL
debuglog("Runtime Admitted: %lu / %lu\n", admissions_control_admitted, admissions_control_capacity);
#endif
#endif /* ADMISSIONS_CONTROL */
}
static inline void
admissions_control_subtract(uint64_t admissions_estimate)
{
#ifdef ADMISSIONS_CONTROL
/* Assumption: Should never underflow */
if (unlikely(admissions_estimate > admissions_control_admitted)) panic("Admissions Estimate underflow\n");
atomic_fetch_sub(&admissions_control_admitted, admissions_estimate);
#ifdef LOG_ADMISSIONS_CONTROL
debuglog("Runtime Admitted: %lu / %lu\n", admissions_control_admitted, admissions_control_capacity);
#endif
#endif /* ADMISSIONS_CONTROL */
}
static inline uint64_t
admissions_control_calculate_estimate(uint64_t estimated_execution, uint64_t relative_deadline)
{
#ifdef ADMISSIONS_CONTROL
assert(relative_deadline != 0);
uint64_t admissions_estimate = (estimated_execution * (uint64_t)ADMISSIONS_CONTROL_GRANULARITY)
/ relative_deadline;
if (admissions_estimate == 0)
panic("Ratio of Deadline to Execution time cannot exceed %d\n", ADMISSIONS_CONTROL_GRANULARITY);
return admissions_estimate;
#else
return 0;
#endif
}
static inline uint64_t
admissions_control_calculate_estimate_us(uint32_t estimated_execution_us, uint32_t relative_deadline_us)
{
#ifdef ADMISSIONS_CONTROL
assert(relative_deadline_us != 0);
return (uint64_t)((uint64_t)(estimated_execution_us * ADMISSIONS_CONTROL_GRANULARITY)) / relative_deadline_us;
#else
return 0;
#endif
}
static inline void
admissions_control_log_decision(uint64_t admissions_estimate, bool admitted)
{
#ifdef LOG_ADMISSIONS_CONTROL
debuglog("Admitted: %lu, Capacity: %lu, Estimate: %lu, Admitted? %s\n", admissions_control_admitted,
admissions_control_capacity, admissions_estimate, admitted ? "yes" : "no");
#endif /* LOG_ADMISSIONS_CONTROL */
}
static inline uint64_t
admissions_control_decide(uint64_t admissions_estimate)
{
uint64_t work_admitted = 1; /* Nominal non-zero value in case admissions control is disabled */
#ifdef ADMISSIONS_CONTROL
if (unlikely(admissions_estimate == 0)) panic("Admissions estimate should never be zero");
uint64_t total_admitted = atomic_load(&admissions_control_admitted);
if (total_admitted + admissions_estimate >= admissions_control_capacity) {
admissions_control_log_decision(admissions_estimate, false);
work_admitted = 0;
} else {
admissions_control_log_decision(admissions_estimate, true);
admissions_control_add(admissions_estimate);
work_admitted = admissions_estimate;
}
#endif /* ADMISSIONS_CONTROL */
return work_admitted;
}
void admissions_control_initialize();
void admissions_control_add(uint64_t admissions_estimate);
void admissions_control_subtract(uint64_t admissions_estimate);
uint64_t admissions_control_calculate_estimate(uint64_t estimated_execution, uint64_t relative_deadline);
uint64_t admissions_control_calculate_estimate_us(uint32_t estimated_execution_us, uint32_t relative_deadline_us);
void admissions_control_log_decision(uint64_t admissions_estimate, bool admitted);
uint64_t admissions_control_decide(uint64_t admissions_estimate);

114
runtime/src/admissions_control.c
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#include <stdatomic.h>
#include <unistd.h>
#include "admissions_control.h"
#include "debuglog.h"
#include "client_socket.h"
/*
* Unitless estimate of the instantaneous fraction of system capacity required to complete all previously
* admitted work. This is used to calculate free capacity as part of admissions control
*
* The estimated requirements of a single admitted request is calculated as
* estimated execution time (cycles) / relative deadline (cycles)
*
* These estimates are incremented on request acceptance and decremented on request completion (either
* success or failure)
*/
_Atomic uint64_t admissions_control_admitted;
uint64_t admissions_control_capacity;
const double admissions_control_overhead = 0.2;
void
admissions_control_initialize()
{
#ifdef ADMISSIONS_CONTROL
atomic_init(&admissions_control_admitted, 0);
admissions_control_capacity = runtime_worker_threads_count * ADMISSIONS_CONTROL_GRANULARITY
* ((double)1.0 - admissions_control_overhead);
#endif
}
void
admissions_control_add(uint64_t admissions_estimate)
{
#ifdef ADMISSIONS_CONTROL
assert(admissions_estimate > 0);
atomic_fetch_add(&admissions_control_admitted, admissions_estimate);
#ifdef LOG_ADMISSIONS_CONTROL
debuglog("Runtime Admitted: %lu / %lu\n", admissions_control_admitted, admissions_control_capacity);
#endif
#endif /* ADMISSIONS_CONTROL */
}
void
admissions_control_subtract(uint64_t admissions_estimate)
{
#ifdef ADMISSIONS_CONTROL
/* Assumption: Should never underflow */
if (unlikely(admissions_estimate > admissions_control_admitted)) panic("Admissions Estimate underflow\n");
atomic_fetch_sub(&admissions_control_admitted, admissions_estimate);
#ifdef LOG_ADMISSIONS_CONTROL
debuglog("Runtime Admitted: %lu / %lu\n", admissions_control_admitted, admissions_control_capacity);
#endif
#endif /* ADMISSIONS_CONTROL */
}
uint64_t
admissions_control_calculate_estimate(uint64_t estimated_execution, uint64_t relative_deadline)
{
#ifdef ADMISSIONS_CONTROL
assert(relative_deadline != 0);
uint64_t admissions_estimate = (estimated_execution * (uint64_t)ADMISSIONS_CONTROL_GRANULARITY)
/ relative_deadline;
if (admissions_estimate == 0)
panic("Ratio of Deadline to Execution time cannot exceed %d\n", ADMISSIONS_CONTROL_GRANULARITY);
return admissions_estimate;
#else
return 0;
#endif
}
uint64_t
admissions_control_calculate_estimate_us(uint32_t estimated_execution_us, uint32_t relative_deadline_us)
{
#ifdef ADMISSIONS_CONTROL
assert(relative_deadline_us != 0);
return (uint64_t)((uint64_t)(estimated_execution_us * ADMISSIONS_CONTROL_GRANULARITY)) / relative_deadline_us;
#else
return 0;
#endif
}
void
admissions_control_log_decision(uint64_t admissions_estimate, bool admitted)
{
#ifdef LOG_ADMISSIONS_CONTROL
debuglog("Admitted: %lu, Capacity: %lu, Estimate: %lu, Admitted? %s\n", admissions_control_admitted,
admissions_control_capacity, admissions_estimate, admitted ? "yes" : "no");
#endif /* LOG_ADMISSIONS_CONTROL */
}
uint64_t
admissions_control_decide(uint64_t admissions_estimate)
{
uint64_t work_admitted = 1; /* Nominal non-zero value in case admissions control is disabled */
#ifdef ADMISSIONS_CONTROL
if (unlikely(admissions_estimate == 0)) panic("Admissions estimate should never be zero");
uint64_t total_admitted = atomic_load(&admissions_control_admitted);
if (total_admitted + admissions_estimate >= admissions_control_capacity) {
admissions_control_log_decision(admissions_estimate, false);
work_admitted = 0;
} else {
admissions_control_log_decision(admissions_estimate, true);
admissions_control_add(admissions_estimate);
work_admitted = admissions_estimate;
}
#endif /* ADMISSIONS_CONTROL */
return work_admitted;
}

2
runtime/src/listener_thread.c
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#include <stdint.h>
#include <unistd.h>
#include "arch/getcycles.h"
#include "client_socket.h"
#include "global_request_scheduler.h"
#include "generic_thread.h"
#include "listener_thread.h"

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