Facebook imiphumela yokuhlolwa nge-algorithm entsha yokulawula ukuminyana - , elungiselelwe ukudlulisa okuqukethwe kwevidiyo. I-algorithm yahlongozwa abacwaningi abavela eMassachusetts Institute of Technology. I-COPA prototype ehlongozwayo ukuze ihlolwe ibhalwe ngo-C++, ilayisensi ngaphansi kwe-MIT futhi ifakwe kuyo - ukuqaliswa kwephrothokholi ye-QUIC eyenziwa ku-Facebook.
I-algorithm ye-COPA igxile ekuxazululeni izinkinga eziphakama lapho kuhanjiswa ividiyo ngenethiwekhi. Kuya ohlotsheni lwevidiyo, izidingo ezicishe zifane zibekwe kuma-algorithms okulawula ukuminyana - kuvidiyo esebenzisanayo, kuyadingeka ukuqinisekisa ukubambezeleka okuncane, ngisho nezindleko zekhwalithi, futhi lapho kusakazwa ividiyo yekhwalithi ephezulu elungiselelwe kusengaphambili, kubekwa kuqala. ekugcineni izinga. Ngaphambilini, abathuthukisi bohlelo lokusebenza bebekhawulelwe ekhonweni lokusebenzisa ama-algorithms ahlukene kuye ngekhwalithi noma izidingo zokubambezeleka. Abacwaningi abathuthukise i-COPA bazame ukudala i-algorithm yendawo yonke yokulawula ukuminyana kwevidiyo ye-TCP engenziwa ngendlela oyifisayo ngokusekelwe ezidingweni zevidiyo.
Umsebenzi we-algorithm yokulawula ukuminyana ukunquma ibhalansi efanele lapho kuthunyelwa amaphakethe - ukuthumela amaphakethe amaningi kakhulu kungaholela ekulahlekeni kwephakethe kanye nokuncipha kokusebenza ngenxa yesidingo sokuwathumela kabusha, futhi ukuthumela kancane kakhulu kuholela ekubambezelekeni, okuphinde kuthinte kabi ukusebenza. . Iphrothokholi ye-QUIC yakhethelwa izivivinyo, njengoba ivumela ukusetshenziswa kwama-algorithms okulawula ukuminyana endaweni yomsebenzisi ngaphandle kokuphazamisa i-kernel.
Ukuze kuvinjelwe ukuminyana kwesiteshi sokuxhumana, i-COPA isebenzisa ukumodela kwezici zesiteshi ngokusekelwe ekuhlaziyeni izinguquko ekubambezelekeni ngesikhathi sokulethwa kwephakethe (i-COPA inciphisa usayizi wewindi lokuminyana njengoba ukubambezeleka kuyanda, ilawula ukuthi ukubambezeleka kuqale ukwanda ngisho nasesiteji ngaphambi kokulahlekelwa kwephakethe) . Ibhalansi phakathi kokubambezeleka nokuphumayo ilungiswa kusetshenziswa ipharamitha ye-delta ekhethekile. Ukwandisa i-delta kukhulisa ukuzwela ekubambezelekeni kodwa kunciphisa ukuphuma, kuyilapho ukwehla kwe-delta kuvumela ukuphuma okuphezulu ngezindleko zokunyuka ukubambezeleka. I-Delta=0.04 ichazwa njengebhalansi efanele phakathi kwekhwalithi nokubambezeleka.
Ngokusekelwe kusevisi yokusakaza ye-Facebook Live, i-COPA ihlolwe ngokuqhathaniswa nama-algorithms adumile e-CUBIC kanye ne-BBR. I-algorithm ye-CUBIC ezenzakalelayo ku-Linux iwukukhulisa kancane kancane usayizi wewindi lokuminyana kuze kube yilapho ukulahleka kwephakethe kwenzeka, ngemva kwalokho usayizi wewindi ugoqelwa emuva kunani ngaphambi kokuba kuqale ukulahlekelwa.
I-CUBIC ishiya okuningi okufiselekayo ekubhafa kwephakethe kumishini yesimanje yenethiwekhi, okunciphisa ukwehla kwephakethe. I-algorithm yokulawula ukuminyana ayiqapheli ukubhafa futhi iyaqhubeka nokwandisa isivinini ngisho noma isiteshi sesivele siminyene ngokomzimba. Amaphakethe angathunyelwanga afakwa kubhafa esikhundleni sokulahlwa, futhi i-algorithm yokulawula ukuminyana ye-TCP ingena kuphela lapho ibhafa igcwele futhi ayikwazi ukulinganisa izinga lokugeleza nesivinini sesixhumanisi esibonakalayo. Ukuze kuxazululwe le nkinga, i-Google iphakamise i-algorithm ye-BBR ethuthukisiwe ebikezela umkhawulokudonsa otholakalayo ngokuhlolwa okulandelanayo kanye nokulinganisa kwesikhathi sokuya nokubuya (RTT).
Nge-delta=0.04, izinkomba ze-COPA kuvele ukuthi ziseduze ne-CUBIC ne-BBR. Ezivivinyweni ezenziwa ngoxhumo lwenethiwekhi olunesivinini esikhulu ngokubambezeleka kokudluliswa kwephakethe eliphansi, i-COPA ithole ukubambezeleka okuphansi (479 ms) uma kuqhathaniswa ne-CUBIC (499 ms), kodwa yehla kancane ngemuva kwe-BBR (462 ms). Lapho ikhwalithi yokuxhuma yehla, i-COPA ibonise imiphumela engcono kakhulu - ukubambezeleka bekungaphansi ngo-27% kunalapho kusetshenziswa i-CUBIC ne-BBR.
Ngesikhathi esifanayo, esiteshini sokuxhumana esingesihle, i-COPA ne-BBR yenza kwaba nokwenzeka ukuzuza umphumela ophakeme kakhulu uma kuqhathaniswa ne-CUBIC. Inzuzo ye-BBR, uma iqhathaniswa ne-CUBIC, ibingu-4.8% no-5.5%, kanti i-COPA - 6.2% no-16.3%.
Source: opennet.ru