Facebook ya haɓaka katin PCIe mai buɗewa tare da agogon atomic

Kwanaki kadan da suka gabata aka fitar da labarin cewa Facebook ya buga abubuwan da suka shafi halittar jirgin PCIe, abin da na haɗaaiwatar da ƙaramin agogon atomic da mai karɓar GNSS.

Da farko an ƙera hukumar azaman na’urar zamani, ta ba da damar amfani da nau'ikan kwakwalwan agogon atomic agogo da keɓaɓɓun kayan kasuwanci da kayayyaki na GNSS, kamar SA5X, mRO-50, SA.45s, da u-blox RCB-F9T. Orolia ta yi niyyar fara samar da allunan da aka gama don ƙayyadaddun bayanai.

Katin lokaci ana haɓaka shi azaman wani ɓangare na ƙarin aikin na'urar lokaci na duniya an yi niyya don samar da abubuwan haɗin don ƙirƙirar sabobin lokaci na farko (Jagorar Lokaci) (Buɗe Lokacin Sabis) waɗanda za a iya aiwatarwa a cikin kayan aikin ku kuma ana amfani da su, misali, don tsara aiki tare na lokaci a cibiyoyin bayanai.

Amfani da sabar uwar garke yana ba ku damar dogaro da sabis na cibiyar sadarwa na waje don daidaita daidai lokacin, da kasancewar agogon atomic da aka gina yana ba da babban matakin cin gashin kai idan aka gaza a karɓar bayanai daga tsarin tauraron dan adam (misali saboda yanayin yanayi ko hare -hare).

Sabuwar tsarin gine-ginen zamani na NTP yana amfani da Stratum 1, muhimmin sashi wanda ke da alaƙa kai tsaye zuwa tushen lokaci mai iko, kamar tsarin tauraron dan adam na duniya (GNSS) ko agogon cesium.

Da peculiarity na aikin shine don gina uwar garken lokaci na farko, zaka iya amfani da sabar al'ada dangane da gine -ginen x86, wanda ya haɗa da katin cibiyar sadarwa na al'ada da katin lokaci.

A kan uwar garken da aka ce, ana samun ainihin lokacin bayanai daga tauraron dan adam ta hanyar GNSS da agogon atomic yana aiki azaman oscillator mai karko sosai, yana ba da damar kiyaye madaidaicin matakin idan babu bayanin da aka samu ta hanyar GNSS. Mai yiwuwa karkacewa daga ainihin lokacin idan ba a iya samun bayanai ta hanyar GNSS akan kwamitin da aka gabatar an kiyasta kusan nanoseconds 300 a kowace rana.

Direban ocp_pt an shirya don Linux y an tsara za a haɗa shi a cikin babban kernel Linux 5.15.

Mai sarrafawa yana aiwatar da musaya PTP POSIX ( / dev / ptp2), GNSS ta tashar jiragen ruwa / dev / ttyS7, agogon atomic ta tashar jiragen ruwa / dev / ttyS8 da na'urori biyu i2c / dev / i2c- *, wanda za'a iya samun damar agogon kayan aiki (PHC) daga yanayin mai amfani.

Lokacin fara sabar NTP (Network Time Protocol), ana ba da shawarar yin amfani da Chrony da NTPd, kuma lokacin fara sabar PTP (Precision Time Protocol), ana ba da shawarar yin amfani da ptp4u ko ptp4l a haɗe tare da tari na phc2sys don samar da kwafin ƙimar lokaci daga agogon atomic zuwa katin cibiyar sadarwa.

Tsarin aiki na aikin mai karɓar GNSS da agogon atomic ana iya yin shi a cikin kayan masarufi da software. Ana aiwatar da ayyukan kayan masarufi na tsarin haɗin gwiwa akan FPGA, kuma sigar software tana aiki a matakin sa ido kai tsaye na matsayin mai karɓar GNSS da agogon atomic daga aikace -aikace kamar ptp4l da chronyd.

Dalilin ci gaban katako mai buɗewa maimakon amfani da shirye-shiryen amfani da mafita da ake samu a kasuwa, shine yanayin haƙƙin irin waɗannan samfuran, wanda baya ba mu damar tabbatar da cewa aiwatarwa daidai ne, software da aka gabatar bai dace ba tare da bukatun tsaro. (A mafi yawan lokuta, ana jigilar shirye -shiryen da suka gabata kuma gyaran rauni zai iya ɗaukar watanni ko ma shekaru don isar da su), kazalika da iyakance iyakancewa da sa ido (SNMP) (ana ba da nasa CLI ko keɓaɓɓen mai amfani da yanar gizo).

Ana iya amfani da allon don tsara aikin sabobin aiki tare na lokaci. Bayanai, makirci, BOM, Gerber, PCB, da fayilolin CAD da ake buƙata don ƙirƙira allon ana sanya su akan GitHub.

Source: https://engineering.fb.com