117 lines
3.6 KiB
Racket
117 lines
3.6 KiB
Racket
#lang racket/base
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;; Measurement of message delivery latency.
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(require racket/match)
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(require prospect)
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(require logbook)
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(provide run)
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(struct ping (src dst timestamp) #:transparent)
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;; (define (current-microseconds)
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;; (* (current-inexact-milliseconds) 1000.0))
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(define (current-microseconds)
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(modulo (* (current-inexact-milliseconds) 1000.0) 1000000000))
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;; (define (current-microseconds)
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;; (truncate (modulo (* (current-inexact-milliseconds) 1000.0) 1000000000)))
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;; (define (current-microseconds)
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;; (inexact->exact (truncate (modulo (* (current-inexact-milliseconds) 1000.0) 1000000000))))
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(define (send-ping src dst)
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(message (ping src dst (current-microseconds))))
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(define (run #:echoer-count [echoer-count 100]
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#:run-time [run-time 10000])
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(define total-latency 0)
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(define total-roundtrips 0)
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(define boot-start-time (current-microseconds))
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(define run-start-time #f)
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(define (rate-at count)
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(/ (* count 2) ;; two messages per roundtrip
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(/ total-latency 1000000.0) ;; latency in seconds
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))
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(define (pinger src dst)
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(spawn (lambda (e s)
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(match e
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[(message 'kickoff)
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(set! run-start-time (current-microseconds))
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(transition s (send-ping src dst))]
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[(message (ping (== dst) (== src) start-time))
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(define stop-time (current-microseconds))
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;; TODO: is there a way of reducing the measurement error here,
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;; perhaps by recording against run-start-time instead of start-time, somehow?
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;; TODO: first, characterize the measurement error
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(define delta (- stop-time start-time))
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(set! total-latency (+ total-latency delta))
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(set! total-roundtrips (+ total-roundtrips 1))
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(when (zero? (modulo total-roundtrips 1000))
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(log-info "After ~a roundtrips, ~a milliseconds; ~a Hz."
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total-roundtrips
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total-latency
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(rate-at total-roundtrips)))
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(transition s
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(if (< (/ (- stop-time run-start-time) 1000.0) run-time)
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(send-ping src dst)
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'()))]
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[_ #f]))
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#f
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(patch-seq (sub (ping dst src ?))
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(sub 'kickoff)
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(pub (ping src dst ?)))))
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(define (echoer id)
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(spawn (lambda (e s)
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(match e
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[(message (ping src (== id) stamp))
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(transition s (message (ping id src stamp)))]
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[_ #f]))
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#f
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(patch-seq (sub (ping ? id ?))
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(pub (ping id ? ?)))))
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(begin
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(run-ground (for/list [(id (in-range echoer-count))] (echoer id))
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(pinger echoer-count 0)
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(message 'kickoff))
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(values total-roundtrips (rate-at total-roundtrips) (- run-start-time boot-start-time))))
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(module+ main
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(define t 10000)
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;; (define E (standard-logbook-entry (default-logbook #:verbose? #t) "minimart" "internal-latency-prospect"))
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;; (define T (logbook-table E "internal-latency"
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;; #:column-spec '(number-of-echoers
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;; secs/msg
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;; msgs/sec
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;; boot-delay-ms
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;; secs/process-booted
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;; roundtrip-count
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;; run-duration-ms)))
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;; Warmup
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(let ()
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(run #:echoer-count 1 #:run-time 1000)
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(run #:echoer-count 10 #:run-time 1000)
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(void))
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;; Real run
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(for ((n
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(list* 1 2 5
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'()#;(let loop ((n 10))
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(if (>= n 30000)
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'()
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(cons (inexact->exact (round n))
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(loop (* n (sqrt (sqrt 2))))))))
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))
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(collect-garbage)
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(collect-garbage)
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(collect-garbage)
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(define-values (count v boot-delay-ms) (run #:echoer-count n #:run-time t))
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(void)#;(write-logbook-datum! T (list n
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(/ 1.0 v)
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v
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boot-delay-ms
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(/ (/ boot-delay-ms 1000.0) n)
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count
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t))))
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