Amfani da kernel na RT (low latency)

Miguel Mayol, babban mai bi ne kuma mai sharhi na wannan rukunin yanar gizon, ya ba da shawarar labarin da aka buga a ciki Matsakaici kan amfani da kernels na RT, wanda muka yanke shawarar bugawa da faɗaɗa shi a wasu sassansa. da Kernel na RT kyale a mafi kyau duka yi a cikin wasu yanayi na musammanMisali, gyaran bidiyo ko amfani da kayan kida na kamala.

Kernel mai yawa

Kernel na Linux, kamar na sauran tsarukan aiki na zamani, ana yin abubuwa da yawa. Wannan yana nufin cewa shirye-shirye da yawa suna gudana a lokaci guda.

A zahiri, wannan ba haka batun yake ba. Abin da kuke yi shine sanya shirye-shiryen cikin layi kuma, ɗayan ɗaya, microprocessor yana aiwatar da su na wani ɗan lokaci. Da zarar an gama wannan, microprocessor ya katse aikin, ya bar shi rabi, ya ba da na gaba. Wannan adadin lokaci ana kiransa jimla ko yanki lokaci, kuma ba lallai bane ya zama na din-din-din.

Misali mai kyau na iya zama mai dafa abinci a cikin mashaya yana shirya jita-jita da yawa a lokaci guda: sandwich na loin, sandwich mai taya, salatin gauraye ... Yanzu na fasa burodin, kunna kwanon rufi, yayin da yake dumama ina wankin letas, da sauransu.

Idan jimla ta yi kadan, ra'ayi na hankali ga mai saurin hankali, kamar mutum, shine cewa a maimakon mai saurin sarrafa abubuwa da ke aiwatar da ayyuka a madadin haka muna da mai saurin sarrafawa ga kowanne daga cikinsu (masu dafa abinci da yawa a girki daya a hankali suna yin kowanne daya kwano daya).

Switchawainiyar aiki yana zuwa da tsada

Yin amfani da yawa ba kyauta ba ne: ya ƙunshi mai sarrafa sama. Lallai, korar aiki daya da lodawa na gaba shine karin aiki. Ana kiran wannan aikin 'sauyawar mahallin' ko 'sauyawa aiki'. Zai zama mafi tsada sosai dangane da CPU don gudanar da shirye-shiryen gaba ɗaya, ɗaya bayan ɗaya, fiye da yankan su cikin 'yanka' da tsalle daga wannan zuwa wancan. Koyaya, tsarin zaiyi asara a cikin ma'amala, ba za mu iya buɗe windows da yawa ba ko, a game da sabar, mu halarci buƙatu da yawa lokaci guda.

Rashin hankali da aiki

Misali idan mai dafa abincin mu ya fefe kilo 20 na prawns da rami kilo 20 na zaitun. Yaya aka tsara aikin?

A cikin wani yanayi mai tsauri, da farko zai fara cire dukkan ciyawar, ya wanke hannuwansa don kauce wa cakuda dandano, sannan kuma ya zare dukkanin zaitun. Za mu wakilce shi kamar haka:

GGGGGGGGGGGGGGGGGGGGG… C AAAAAAAAAAAAAAAAAAAAAAAA…

A gefe guda kuma, zai cire bawon, ya wanke hannunsa, ya huda zaitun, ya wanke hannayensa ... prawn, zaitun, itacen zaitun ... Za mu wakilce shi kamar haka:

GCACCACCACCAGCACCACCAGCACCAGCACCAGCACCAGCACCACGAGCACCAGCACCAGGACACCAGGACCAGGACCAGGACCAGG

'C' yana wakiltar canji a cikin mahallin: wanke hannu, canza kayan aiki ...

A lokaci guda, ma'aikaci yakan tattara buƙatun kwastomomin: "Oneaya da prawns!" ... "withaya da zaitun!" ... kuma ya canza su zuwa kicin.

A farkon lamarin, a ce abokin ciniki ya shigo ya nemi wani yanki na jatan lande. Babu matsala, ana aiki da shi kai tsaye. Amma idan ya nemi zaitun fa? Mai jiran hidimar ba zai iya yi masa hidima ba har sai da aka fuɗe dukkan prawns ɗin. A wannan halin, latency, wanda shine lokacin da yake wucewa daga lokacin da aka gabatar da buƙata har sai an amsa ta, zai yi yawa sosai.

A cikin lamari na biyu, duk abin da abokin ciniki ya nema, za'a same shi a cikin ɗan gajeren lokaci, shima kusan iri ɗaya ne a al'amuran biyu. Latency zai yi ƙasa, amma a farashi: saboda canje-canjen mahallin za'a sami raguwar aiki, fahimta azaman wani ɓangare na lokacin lokacin da CPU ke yin ayyuka kai tsaye kai tsaye, maimakon ayyukan tallafi.

Babu shakka a cikin wannan yanayin mafificiyar mafita za ta kasance ƙasa ta tsakiya, wanda zai dogara da girman rabon da ƙididdigar buƙatun. Tsarin ka'ida shine reshe na lissafi wanda ke da alhakin nazarin waɗannan yanayin da samar da ingantattun mafita.

Kamar yadda kake gani, jinkiri da aiwatarwa sune kishiyoyi. Saboda wannan dalili ba daidai bane a ce rt kernels suna ba da ƙarin aiki. Akasin haka, rage latency yana rage aikin inji kuma saboda haka zabi ne mara kyau ga tsarin da baya bukatar amsoshi masu sauri, kamar su yanar gizo ko sabar bayanan.

Akasin haka, ƙananan ƙarancin latency suna da kyau a cikin yanayi inda ake buƙatar saurin gudu na amsawa ga matsalolin waje, kamar tsarin sarrafa masana'antu ko aikace-aikacen multimedia masu ma'amala, da sanin cewa muna sadaukar da wani ɓangare na ƙarfin inji don tabbatar da saurin saurin .

Abubuwan fifiko

Wani zaɓi mai ban sha'awa a cikin tsarin aiki da yawa shine bada fifiko daban-daban ga ayyuka, ta yadda waɗanda suka fi mahimmanci ke karɓar ƙarin lokaci daga mai sarrafawa da waɗanda ba su da muhimmanci. A cikin kernel na yau da kullun ana yin wannan tare da umarnin 'kyau'. Idan mai dafa abincinmu yana tsammanin zai ba da ƙarin lamuran prawn fiye da zaitun, zai yi kyau ya sami ƙarin lokaci akan na farkon, ba shakka.

Kernel RT (ko rashin ƙarfi)

Matsalar kernel na yau da kullun shi ne cewa ba za a iya katse ayyukan ko'ina ba, dole ne ku jira su don isa wasu wuraren aiwatarwa inda za a dakatar da su don canzawa zuwa wani. Wannan yana gabatar da abin da muke kira latency.

Don sanya shi a hanya mai sauƙi, kernels na RT suna ba da damar katse ayyukan a wasu wurare fiye da kernel na al'ada. Suna iya yi, don haka don yin magana, ƙaramin yanki lokaci, don haka za'a fitar da aikin na yanzu da sauri kuma aikinmu na fifiko zai iya samun damar CPU da wuri. Saboda haka latti zai zama ƙasa.

Bari mu ce wani kernel na RT ya bamu damar barin shrimp rabin peel idan abin da ake buƙata cikin gaggawa a wannan lokacin shine ragar zaitun da wuri-wuri, yayin da a cikin kwaya irin ta yau da kullun zai zama tilas a gama cire pegin.

Baya ga yin yankan yanka, kernels na RT suna da tsarin fifiko mai tsauri da yawa, inda ayyuka masu fifiko ba tare da rahama ba suna sara juna (preempting) don samun ikon sarrafa CPU, rage jinkirin wasu shirye-shiryen duk abin da ya dace don biyan buƙatunku.

Yaushe yake da mahimmanci a yi amfani da kernel na RT?

A lokuta biyu:

1) Lokacin da muke buƙatar ƙarancin jinkiri, ma'ana, halayen sauri na inji. Misali mafi bayyana shine aikin kayan aikin kamala, inda kake buƙatar kayan aikin suyi sauti kai tsaye yayin danna maɓalli akan maɓallin MIDI.

2) Lokacin da muke buƙatar abubuwan fifiko masu mahimmanci, ma'ana, cewa babban aikinmu baya katsewa ta kowane abu a duniya (sai dai idan a cikin bala'i idan CPU yayi nauyi sosai har ya wuce amfani da 100%). Misali, muna yin rikodin zaman sauti tare da Ardor kuma muna kallon alamun nuna ƙarfi suna hawa sama da ƙasa. Babu matsala idan muka rasa wani tsari na wartsakewa muddin ba a katse sautin daga makirufo zuwa babbar faifai ba. Kernel na RT zai rage sanyin fader kamar yadda ya wajaba muddin ba'a rasa samfurin odiyo ba.

Wannan ya ce, gabaɗaya sabbin kernels wadanda ba RT ba sun inganta tsarin tsara su da kuma fifikon kulawa. Idan baku da CPU a iyakar iyawarsa (faɗi ƙasa da 50% amfani) ko kuma idan baku damu da cewa lokaci-lokaci akwai ƙaramin ƙaramin micro (danna) a cikin sautin (abin da ake tsoro xruns), al'ada na kwaya yana ba da cikakkiyar karɓa.

Wane jinkiri ne mai kyau?

Da kaina, kowane abu da ke ƙasa da 10 ms yana da kyau a gare ni kuma daga 20 ms tuni na fara lura da jinkirin a sarari. Akwai mutane da yawa masu buƙata.

Shigarwa

Akan Ubuntu da Kalam:

sudo apt-samun shigar Linux-headers-lowlatency
sudo dace-samun shigar linux-lowlatency
sudo sabuntawa-grub

A farkon farawa zaku sami zaɓuɓɓuka biyu (kwaya ta al'ada da ƙaramar latency).

A cikin Arch da Kalam:

yaourt -S Linux-rt
sudo sabuntawa-grub

Source: Matsakaici