Kana a teburin gudanarwa na na'urar sauya biyan kuɗi da ke tsakanin 'yan kasuwa da masu bayar da kati. A kowane minti kusan ma'amaloli 400 a daƙiƙa suna iso; ana yi wa kowacce maki ta zamba, tana jiran ramin haɗi da babu kowa, kuma ana tura ta ga mai bayarwarta don amsa. Samfurin yana ƙididdige layi, ƙarewar lokaci, sake gwadawar abokan ciniki, sulhun tace zamba da haɗarin amincewa a madadi daga dabarun littafi. Adadin kuɗi yana cikin rukunin kuɗi na gama-gari (u). Na'urar koyo ce kawai — ba shawarar kuɗi, doka ko jari ba.
Abin da za ka koya
Dalilin da ya sa sake gwadawa zai iya kulle na'urar sauyawa da ta cika kaya cikin guguwar sake gwadawa ko da bayan an ƙara ƙarfi — da yadda rage kaya ke karya zagayen.
Yadda iyakar makin zamba ke cinikayya tsakanin asarar zamba da abokan ciniki nagari da aka ƙi, da dalilin da ya sa iyakar da ta dace ke dogara da yawan tushen zamba.
Yadda mai bayarwa guda mai jinkiri ke cika kowane ramin haɗi (dokar Little), da abin da ƙarewar lokaci da sarrafa amincewa a madadi ke kashewa.
Na'urar koyi
Lokaci 0 min
▶Sabar tana hidima
⚙Sabar tana farawa
·Wurin sabar da babu kowa a shiryayye
✓Mai bayarwa yana amsawa yadda ya kamata
⌛Mai bayarwa yana jinkiri ko ya mutu
⇄Sarrafa amincewa a madadi yana kunne
•Ma'amaloli masu shigowa
Sarrafawa
Kowace sabar tana ɗauke da ramukan haɗi 32. Sabar da aka ƙara tana ɗaukar minti 5 kafin ta fara; ana biyan kuɗin kowace sabar, ta fara ko ba ta fara ba.
Yana karɓar mafi yawa 90 % na ƙarfi kuma yana amsa abin da ya wuce nan take da “a sake gwadawa daga baya”, maimakon ya bar shi ya jira a layi kuma lokaci ya ƙare.
Yadda 'yan kasuwa ke sake gwadawa bayan gazawar fasaha (har sau 3). Nan take = cikin minti na gaba; jinkiri = jinkiri mai ƙaruwa bazuwar, matsakaicin jinkiri minti 1, 2 da 4.
Ana ƙin ma'amaloli masu maki a wannan ko sama da shi. Makin yana cikin karkacewar daidaitacce ta zirga-zirgar gaskiya: ƙasa yana nufin ƙarin zamba ya tsaya da ƙarin abokan ciniki nagari da aka ƙi.
Maki da suka yi ƙasa da iyaka da wannan nisa suna samun ƙarin gwaji ga abokin ciniki maimakon yanke hukunci: 85 % na abokan ciniki na gaske suna kammala shi, 5 % na masu zamba suna wucewa. 0 = a kashe.
Tsawon lokacin da ramin haɗi ke jiran amsar mai bayar da kati (issuer). Bayan haka na'urar sauya biyan kuɗi (switch) tana aika soke (reversal) kuma tana amfani da amincewa a madadinsa (stand-in), ko ta ƙi da “mai bayarwa ba ya samuwa”.
Idan mai bayarwa bai amsa a kan lokaci ba, na'urar sauyawa tana amincewa a madadinsa har zuwa wannan adadi. Kowace amincewa a madadi haɗari ne da mai bayarwa bai taɓa dubawa ba. 0 = a kashe.
Alamomi
Yawan amincewa da abokan ciniki nagari
99.9%
daidai
Lokacin amincewa
330ms
daidai
Yawan zamba (kaso na adadin da aka amince)
10.4bp
daidai
Ramukan haɗi da ke aiki
69%
daidai
Yawan amincewa, masu bayarwa lafiyayyu
99.9 %
Abokan ciniki nagari da ƙa'idar zamba ta ƙi
1.3 ‰
Ma'amalolin da aka tura ƙarin tabbatarwa
0.0 %
Zambar da aka tsayar
31 %
Sababbin ma'amaloli
400 tx/s
Kayan da aka bayar (sabo + sake gwadawa)
400 tx/s
Sake gwadawa
0 tx/s
Waɗanda aka rage (an amsa “a sake gwadawa daga baya”)
0 tx/s
Waɗanda aka jefar a layi
0.0 %
Ƙarewar lokutan masu bayarwa
0.0 %
Amincewa a madadi
0 tx/s
Sabobi masu aiki
6
Sabobi da ke farawa
0
Gudun kuɗin sabobi
36 u/h
Kuɗin sabobi har yanzu
0 u
Haɗarin amincewa a madadi
0.00 M u
Zambar da aka amince har yanzu
0.00 M u
Ma'amaloli nagari da aka rasa har yanzu
0.0 k tx
Ma'amaloli da ke jiran sake gwadawa
0 tx
Jinkirin rukunin masu bayarwa B (matsakaici)
250 ms
Yanayi
Yanayin rikici
Mataki 1 · Tsalle a kololuwar kasuwa
Babbar kasuwar kan layi tana buɗewa a minti na 5 kuma tana ninka zirga-zirga zuwa kusan ma'amaloli 800 a daƙiƙa har tsawon minti 45. Na'urar sauyawa tana aiki da sabobi 6, da aka ƙera wa yini na yau da kullum a kusan 70 % na aiki. 'Yan kasuwa suna sake gwada kowace gazawar fasaha nan take. Riƙe abokan ciniki nagari a matsayin waɗanda aka amince da kuma amsoshi masu sauri ba tare da sayen ƙarfin da ba ka buƙata ba.
Matsakaicin amincewa da abokan ciniki nagari ≥ 95 % tun daga fara kasuwar
Matsakaicin lokacin amincewa ≤ 500 ms
Kuɗin sabobi ≤ 75 u
Mataki 2 · Guguwar zamba
A minti na 5 an fara amfani da gungun bayanan katin da aka sace: kason zamba na zirga-zirga yana tsalle daga 0.1 % zuwa 1 %. An saita iyakar ƙi don kwanakin yau da kullum (3σ) kuma ƙarin tabbatarwa a kashe yake. Saukar da yawan zamba ba tare da juya abokan ciniki nagari ba.
Matsakaicin yawan zamba ≤ 25 bp
Matsakaicin amincewa da abokan ciniki nagari ≥ 98 %
Abokan ciniki nagari da ƙa'ida ta ƙi ≤ 5 ‰
Mataki 3 · Katsewar mai bayarwa
A minti na 5 masu bayarwa na rukunin B — kashi ɗaya cikin huɗu na dukkan zirga-zirga — suna sauka zuwa matsakaicin lokacin amsa na daƙiƙa 12. Na'urar sauyawa tana jira har 8 s don amsa, ba ta da amincewa a madadi, kuma tana aiki da sabobi 6. Ci gaba da bi wa abokan ciniki na masu bayarwa lafiyayyu hidima, yi wa rukunin B hidima gwargwadon aminci, kuma riƙe haɗarin amincewa a madadi da kuɗi cikin iko.
Matsakaicin amincewa da abokan ciniki na masu bayarwa lafiyayyu ≥ 90 %
Matsakaicin amincewa da abokan ciniki nagari ≥ 86 %
Haɗarin amincewa a madadi ≤ 9 M u
Kuɗin sabobi ≤ 65 u
Tushe — samfurin da ke bayan lambobin
Kowace alaƙa da na'urar koyi ke amfani da ita, tare da tushenta. Ƙayyadaddun ƙimomin da aka yi wa alama a matsayin zato daidaitawa ne na misali.
Sababbin ma'amaloli suna zuwa da gudun tushe ninka ƙaruwar tallace-tallace; ƙidayar kowane minti bazuwar ce (Poisson, kimantawar al'ada) tare da ɗan tsiƙewa.
λ(t) = base × surge(t) (2-min lag); count/min ≈ N(60λ, √(60λ)) × (1 + N(0, 0.03))[2]Zato: adadin ramuka, lokutan hidima da na mai bayarwa, rabuwar maki, yawan wucewar ƙarin tabbatarwa, kason aikin da aka ɓata, adadin kuɗi da farashi ƙididdiga ne na misali ga na'urar sauyawa ta matsakaicin girma, ba ƙididdigar wata hanyar sadarwa ta gaske ba.
Makin zamba na binormal: makin gaskiya da na zamba lankwasa biyu ne na al'ada da suke nisan d′; iyakar tana zaɓar wuri a lankwasar ROC.
genuine score ~ N(0,1), fraud ~ N(d′,1), d′ = 2.5; FPR(t) = 1 − Φ(t), TPR(t) = 1 − Φ(t − d′); AUC = Φ(d′/√2) ≈ 0.96[6][7]Zato: adadin ramuka, lokutan hidima da na mai bayarwa, rabuwar maki, yawan wucewar ƙarin tabbatarwa, kason aikin da aka ɓata, adadin kuɗi da farashi ƙididdiga ne na misali ga na'urar sauyawa ta matsakaicin girma, ba ƙididdigar wata hanyar sadarwa ta gaske ba.
Iyaka mafi arha: a ƙi idan rabon yiwuwa ya wuce rabon kuɗi da aka auna da yawan tushe — idan zamba ta ninka sau goma tana motsawa ƙasa da ln 10 / d′ ≈ 0.9σ.
Ƙarin tabbatarwa: ana ƙalubalantar maki da ke cikin ɓangaren ƙasa da iyaka maimakon a yanke hukunci.
scores in [t − b, t) are challenged: genuine pass 85 %, fraud pass 5 %; scores ≥ t declined[10]Zato: adadin ramuka, lokutan hidima da na mai bayarwa, rabuwar maki, yawan wucewar ƙarin tabbatarwa, kason aikin da aka ɓata, adadin kuɗi da farashi ƙididdiga ne na misali ga na'urar sauyawa ta matsakaicin girma, ba ƙididdigar wata hanyar sadarwa ta gaske ba.
Jinkirin mai bayarwa na exponential ne; ana riƙe rami har tsawon jinkirin ko ƙarewar lokaci, wanda ya fara zuwa.
L ~ Exp(mean m); E[min(L, T)] = m(1 − e^(−T/m)), P(L > T) = e^(−T/m); S = 80 ms + forwarded × Σ share·E[min(L,T)][2][9]
Dokar Little: ramukan da ke aiki = yawan zuwa × lokacin riƙewa.
Erlang C: yiwuwar ma'amala ta jira ramin da babu kowa, da yiwuwar ta jira fiye da ƙarewar lokacin layi na 2 s.
P(W > 2 s) = C(a, N)·e^(−(N/S − λ)·2 s), a = λS; mean wait = C / (N/S − λ)[1][2]
Fiye da ƙarfi na'urar sauyawa tana kuma kashe aiki kan buƙatun da za ta jefar daga baya, don haka amfanin fitarwa yana faɗuwa yayin da kaya ke ƙaruwa; rage kaya yana ƙin abin da ya wuce da arha.
λ ≥ N/S: goodput = (N/S − ω·λ)/(1 − ω), ω = 0.3; load shedding admits ≤ 0.9·N/S and answers the rest at once[4][5]Zato: adadin ramuka, lokutan hidima da na mai bayarwa, rabuwar maki, yawan wucewar ƙarin tabbatarwa, kason aikin da aka ɓata, adadin kuɗi da farashi ƙididdiga ne na misali ga na'urar sauyawa ta matsakaicin girma, ba ƙididdigar wata hanyar sadarwa ta gaske ba.
Sake gwadawa na abokin ciniki: ana sake gwada kowace gazawar fasaha har sau uku, nan take ko da jinkiri mai ƙaruwa bazuwar.
failed attempt → retry with p = 0.95, ≤ 3 retries; immediate: next minute; backoff: delay ~ Exp(mean 1, 2, 4 min)[4][5]Zato: adadin ramuka, lokutan hidima da na mai bayarwa, rabuwar maki, yawan wucewar ƙarin tabbatarwa, kason aikin da aka ɓata, adadin kuɗi da farashi ƙididdiga ne na misali ga na'urar sauyawa ta matsakaicin girma, ba ƙididdigar wata hanyar sadarwa ta gaske ba.
Ƙarewar lokacin mai bayarwa, soke da amincewa a madadi: adadin kuɗi na lognormal ne, don haka kason da ke ƙasa da iyaka da yawan da aka amince suna fitowa daga CDF na al'ada.
issuer timeout → reversal; stand-in approves if amount ≤ limit: P = Φ((ln L − μ)/σ), volume = e^(μ+σ²/2)·Φ((ln L − μ − σ²)/σ)[9][11]
Yawan zamba a basis points na adadin da aka amince; ana amfani da 13 bp a matsayin ma'aunin kwatance ga ƙananan biyan kuɗi na kati daga nesa.
Sauran madaidaitan aiki da samfurin ke amfani da su.
32 slots per server, 2–24 servers, +5 min boot, 6 u per server-hour · switch time 80 ms · queue timeout 2 s · issuer latency 250 ms (group B = 25 % of traffic, ±15 % per minute) · amounts lognormal, median 40 u, σ = 1, fraud ×1.5 · ω = 0.3 · shedding at 90 % · reversal = 80 ms of switch timeZato: adadin ramuka, lokutan hidima da na mai bayarwa, rabuwar maki, yawan wucewar ƙarin tabbatarwa, kason aikin da aka ɓata, adadin kuɗi da farashi ƙididdiga ne na misali ga na'urar sauyawa ta matsakaicin girma, ba ƙididdigar wata hanyar sadarwa ta gaske ba.
Rashin tsari: mai samar da mulberry32 mai iri; rarrabawar da aka yi amfani da su — uniform, exponential (inverse CDF), normal (Box–Muller), Poisson (Knuth). Ana nuna iri kuma ana iya raba shi.
M. Harchol-Balter — Performance Modeling and Design of Computer Systems: Queueing Theory in Action (M/M/k, capacity provisioning) — Cambridge University Press, 2013