Facebook cov txiaj ntsig ntawm kev sim nrog cov txheej txheem tswj kev sib tsoo tshiab - , tau tsim kho kom zoo rau kev xa cov ntsiab lus video. Cov kws tshawb fawb los ntawm Massachusetts Institute of Technology tau tawm tswv yim txog cov algorithm. Tus qauv COPA xa mus rau kev sim yog sau ua C ++. nyob rau hauv daim ntawv tso cai MIT thiab suav nrog hauv — kev siv cov txheej txheem QUIC uas tau tsim tawm ntawm Facebook.
Tus txheej txheem COPA yog tsim los daws cov teeb meem ntawm kev xa video hla lub network. Nyob ntawm hom video, cov txheej txheem tswj kev sib tsoo ntsib cov kev cai sib txawv: kev sib tham video xav tau qhov latency tsawg kawg nkaus, txawm tias tus nqi ntawm qhov zoo, thaum cov yeeb yaj kiab ua ntej tsim tawm, qhov tseem ceeb tshaj plaws yog kev tswj hwm qhov zoo. Yav dhau los, cov neeg tsim khoom siv tau txwv rau kev siv cov txheej txheem sib txawv raws li qhov zoo lossis qhov latency xav tau. Cov kws tshawb fawb uas tsim COPA tau sim tsim ib qho txheej txheem thoob ntiaj teb rau kev tswj hwm TCP congestion thaum lub sijhawm xa video uas tuaj yeem hloov kho rau cov kev cai video tshwj xeeb.
Tus txheej txheem tswj kev sib tsoo txiav txim siab qhov sib npaug zoo tshaj plaws thaum xa cov pob ntawv. Kev xa ntau dhau pob ntawv tuaj yeem ua rau pob ntawv poob thiab kev ua haujlwm raug nplua vim qhov xav tau rov xa lawv, thaum xa qeeb dhau ua rau muaj kev ncua sijhawm, uas kuj cuam tshuam tsis zoo rau kev ua haujlwm. Tus txheej txheem QUIC tau raug xaiv rau kev sim vim nws tso cai rau cov txheej txheem tswj kev sib tsoo kom siv tau rau hauv qhov chaw neeg siv yam tsis cuam tshuam nrog lub kernel.
Txhawm rau tiv thaiv kev sib tsoo ntawm cov channel, COPA siv cov qauv kev ua haujlwm ntawm cov channel raws li kev tshuaj xyuas ntawm kev hloov pauv ntawm kev xa khoom qeeb (COPA txo qhov loj ntawm lub qhov rais sib tsoo thaum kev ncua ntxiv, siv qhov tseeb tias kev ncua pib nce txawm tias ua ntej pob poob tshwm sim). Qhov sib npaug ntawm kev ncua thiab throughput yog tswj hwm siv cov parameter tshwj xeeb, delta. Kev nce delta ua rau muaj kev cuam tshuam qeeb tab sis txo throughput, thaum kev txo delta tso cai rau throughput siab dua ntawm tus nqi ntawm kev ncua ntxiv. Tus nqi delta ntawm 0.04 yog txhais tias yog qhov sib npaug zoo tshaj plaws ntawm qhov zoo thiab kev ncua.
COPA tau raug sim tawm tsam cov algorithms CUBIC thiab BBR nrov siv cov kev pabcuam Facebook Live streaming. Lub CUBIC algorithm yog siv los ntawm lub neej ntawd hauv Linux thiab ua rau maj mam nce ntxiv ntawm qhov loj ntawm lub qhov rais kom txog thaum pob ntawv poob, tom qab ntawd qhov loj ntawm lub qhov rais raug dov rov qab mus rau tus nqi ua ntej qhov poob pib.
CUBIC qhov kev tiv thaiv pob ntawv nruab nrab ntawm cov khoom siv network niaj hnub no tsis muaj ntau yam uas yuav tsum tau ua, vim nws ua rau cov pob ntawv poob qeeb. Lub algorithm tswj kev sib tsoo tsis paub txog qhov kev tiv thaiv no thiab txuas ntxiv nce qhov ceev txawm tias qhov txuas twb muaj kev sib tsoo lawm. Cov pob ntawv tsis tau xa yog buffered es tsis yog poob, thiab TCP congestion control algorithm tsuas yog pib thaum lub buffer puv thiab tsis tuaj yeem sib npaug qhov nrawm nrog qhov ceev ntawm qhov txuas. Txhawm rau daws qhov teeb meem no, Google tau tawm tswv yim txog BBR algorithm uas tau txhim kho uas kwv yees qhov bandwidth muaj los ntawm kev kuaj xyuas ua ntu zus thiab kev kwv yees lub sijhawm ncig (RTT).
Ntawm delta = 0.04, COPA qhov kev ua tau zoo ze li ntawm CUBIC thiab BBR. Hauv kev sim ua ntawm kev sib txuas network ceev ceev nrog lub pob ntawv qis latency, COPA tau txais latency qis dua (479 ms) dua li CUBIC (499 ms), tab sis poob qis me ntsis tom qab BBR (462 ms). Thaum qhov zoo ntawm kev sib txuas poob qis, COPA tau qhia txog cov txiaj ntsig zoo tshaj plaws - latency qis dua 27% dua li ntawm CUBIC thiab BBR.
Ntxiv mus, ntawm txoj kev sib txuas lus tsis zoo, COPA thiab BBR tau txais txiaj ntsig ntau dua piv rau CUBIC. BBR qhov txiaj ntsig ntawm kev xa xov ntau dua CUBIC yog 4.8% thiab 5.5%, thaum COPA yog 6.2% thiab 16.3%.
Tau qhov twg los: opennet.ru
