Facebook zotsatira zoyeserera pogwiritsa ntchito njira yatsopano yowongolera kusokonekera - , wokometsedwa kuti azitumiza mavidiyo. Algorithm idapangidwa ndi ofufuza ochokera ku Massachusetts Institute of Technology. Chitsanzo cha COPA chomwe akufuna kuti chiyesedwe chalembedwa mu C++, zololedwa pansi pa MIT ndikuphatikizidwa - kukhazikitsidwa kwa protocol ya QUIC yomwe ikupangidwa pa Facebook.
Algorithm ya COPA imayang'ana kwambiri kuthetsa mavuto omwe amadza potumiza makanema pamaneti. Kutengera ndi mtundu wa kanema, pafupifupi zofunikira zotsutsana zimayikidwa pamayendedwe owongolera - pavidiyo yolumikizana, ndikofunikira kuwonetsetsa kuti kuchedwetsa pang'ono, ngakhale kuwononga mtundu wake, komanso kuwulutsa kanema wapamwamba kwambiri wokonzedweratu, choyambirira chimaperekedwa. kusunga khalidwe. M'mbuyomu, opanga mapulogalamu anali ochepa kutha kugwiritsa ntchito ma aligorivimu osiyanasiyana kutengera mtundu kapena zofunikira za latency. Ofufuza omwe adapanga COPA adayesa kupanga algorithm yapadziko lonse lapansi yowongolera kusokonekera kwamavidiyo a TCP omwe angasinthidwe malinga ndi zofunikira zamavidiyo.
Ntchito ya congestion control algorithm ndiyo kudziwa momwe mungakhalire bwino potumiza mapaketi - kutumiza mapaketi ochulukirapo kungayambitse kutayika kwa paketi ndi kuwonongeka kwa magwiridwe antchito chifukwa chofuna kuwatumizanso, ndipo kutumiza pang'onopang'ono kumabweretsa kuchedwa, komwe kumakhudzanso magwiridwe antchito. . Protocol ya QUIC idasankhidwa pazoyeserera, chifukwa imalola kukhazikitsidwa kwa njira zowongolera zosokoneza m'malo ogwiritsa ntchito popanda kusokoneza kernel.
Pofuna kupewa kusokonekera kwa njira zoyankhulirana, COPA imagwiritsa ntchito kutengera mawonekedwe a tchanelo kutengera kuwunika kwa kusintha kwa kuchedwa panthawi yopereka paketi (COPA imachepetsa kukula kwa zenera lazambiri pomwe kuchedwa kumachulukirachulukira, ndikuwongolera kuti kuchedwetsa kumayamba kuwonjezeka ngakhale pagawo kusanachitike kutayika kwa paketi) . Kuwerengera pakati pa kuchedwa ndi kutulutsa kumasinthidwa pogwiritsa ntchito delta parameter yapadera. Kuchulukirachulukira kwa delta kumawonjezera chidwi pakuchedwetsa koma kumachepetsa kutulutsa, pomwe kuchepa kwa delta kumathandizira kutulutsa kwakukulu pamtengo wowonjezereka wa latency. Delta = 0.04 imatanthauzidwa ngati mulingo woyenera pakati pa khalidwe ndi latency.
Kutengera ntchito ya Facebook Live yotsatsira, COPA idayesedwa poyerekeza ndi ma algorithms otchuka a CUBIC ndi BBR. Chotsatira cha CUBIC algorithm pa Linux ndikuwonjezera pang'onopang'ono kukula kwa zenera lachisokonezo mpaka kutayika kwa paketi, pambuyo pake kukula kwazenera kumabwereranso kumtengo kusanayambe kutayika.
CUBIC imasiya zambiri zomwe zimafunidwa pakusunga mapaketi pazida zamakono zamakono, zomwe zimachepetsa kutsika kwa paketi. The congestion control algorithm sadziwa za buffering ndipo ikupitilizabe kuthamanga ngakhale tchanelo chitakhala chodzaza kale. Mapaketi osatumizidwa amasungidwa m'malo motayidwa, ndipo ma algorithm owongolera a TCP amangoyambira pomwe buffer ili yodzaza ndipo sangathe kulinganiza kuthamanga kwa liwiro la ulalo wakuthupi. Kuti athetse vutoli, Google yakonza njira yosinthira ya BBR yomwe imaneneratu kuchuluka kwa bandiwifi yomwe ilipo kudzera pakufufuza motsatizana komanso kuyerekeza kwa nthawi yobwerera (RTT).
Ndi delta = 0.04, zizindikiro za COPA zidakhala pafupi ndi CUBIC ndi BBR. M'mayeso omwe adachitika pa intaneti yothamanga kwambiri komanso kuchedwa kwapaketi yotumiza, COPA idapeza latency yotsika (479 ms) poyerekeza ndi CUBIC (499 ms), koma idagwera kuseri kwa BBR (462 ms). Pamene khalidwe kugwirizana utachepa, COPA anasonyeza zotsatira zabwino - kuchedwa anali 27% kutsika kuposa pamene ntchito CUBIC ndi BBR.
Panthawi imodzimodziyo, pa njira yolankhulirana yosauka, COPA ndi BBR zinapangitsa kuti zitheke kupindula kwambiri poyerekeza ndi CUBIC. Kupindula kwa BBR, poyerekeza ndi CUBIC, kunali 4.8% ndi 5.5%, ndi COPA - 6.2% ndi 16.3%.
Source: opennet.ru