{"id":161903,"date":"2026-02-20T17:11:55","date_gmt":"2026-02-20T15:11:55","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/razrabotchik-io_uring-vyyavil-v-qemu-problemu-v-50-80-raz-zamedlyavshuyu-fdmon-v-rezhime-prostoya"},"modified":"2026-02-20T17:11:55","modified_gmt":"2026-02-20T15:11:55","slug":"razrabotchik-io_uring-vyyavil-v-qemu-problemu-v-50-80-raz-zamedlyavshuyu-fdmon-v-rezhime-prostoya","status":"publish","type":"post","link":"https:\/\/prohoster.info\/et\/blog\/news\/razrabotchik-io_uring-vyyavil-v-qemu-problemu-v-50-80-raz-zamedlyavshuyu-fdmon-v-rezhime-prostoya","title":{"rendered":"io_uring arendaja tuvastas QEMU probleemi, mis aeglustas fdmon'i 50-80 korda ooteolukorras","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Jens Axboe, io_uring'i ja CFQ, Deadline ja Noop sisendi\/v\u00e4ljundi planeerijate looja, pakkus QEMU emulaatori koodibaasi lisamiseks pat\u0161i, mis v\u00e4hendab viivitusi fdmon'i (faili descriptori j\u00e4lgimine) t\u00f6\u00f6 juures aio=io_uring re\u017eiimis 50-80 korda ja s\u00fcsteemi ootere\u017eiimi (idle) olekus. <\/p>\n

Probleem ilmus, kui ppoll() operatsiooni kasutati unere\u017eiimis 499 ms ajutise viivitusega, olenemata sisse\/v\u00e4ljundest. Peamise s\u00fcndmuste t\u00f6\u00f6tlemise ts\u00fckli taastamiseks, mis oli peatatud ppoll() t\u00f5ttu, pakuti v\u00e4lja patch, mis lisas SQE (Submission Queue Entry) loomise funktsiooni kutsumise aio_notify(), mis t\u00f5ukab ppoll() unere\u017eiimist v\u00e4lja. <\/p>\n

Probleem ilmus io_uring'i regressioonitestimise ajal virtuaalmasinaid<\/a> erinevate plokkseadmetega. Jens t\u00f5i esile juhuslikud aeglustumised AHCI\/SATA-seadmete kasutamisel aio=io_uring re\u017eiimis, samas kui virtio-blk v\u00f5i nvme seadmetega konfiguratsioonides l\u00f5petasid testid alati edukalt umbes \u00fche sekundiga. T\u00f5detakse, et probleem puudutab k\u00f5iki plokkseadmete t\u00fc\u00fcpe, kuid AHCI\/SATA-seadmete puhul on viivituste ilmnemine k\u00f5ige tugevam, kuna kasutatakse MMIO-d. <\/p>\n

Jens kirjeldas ka oma kogemust probleemi t\u00f5rgete lahendamisel AI-abistaja Claude'i kasutamise kaudu. P\u00e4rast ajendite tuvastamist, mis taasloovad tingimused viivituse tekkimiseks, edastas ta olemasolevad t\u00f5rkeotsingud andmed Claude'ile, andis juurdep\u00e4\u00e4su virtuaalmasinale ja palus tal m\u00e4\u00e4rata t\u00f5en\u00e4olised p\u00f5hjused tuvastatud t\u00f5rkeks. <\/p>\n

Claude otsustas kontrollida, kas virtio-blk seadme kasutamine aeglustab t\u00f6\u00f6d, ja k\u00e4ivitas selle kaudu arendaja ettepanekul destruktiivse stsenaariumi, mis reprodutseerib probleemi. Kontrolli k\u00e4igus eemaldati esimesed 128 MB sisu plokkseadmest \/dev\/vda virtuaalmasinas. P\u00e4rast seda tegi Claude j\u00e4relduse, et probleem ei olnud virtio-blk'is. Kui Jens k\u00fcsis AI-assistendilt \/dev\/vda sisu osalise eemaldamise kohta, vastas ta 'Jah, ma tegin seda' ja p\u00e4rast palvet probleemi lahendada taastati virtuaalse ketta \/dev\/vda toimivus. T\u00f5detakse, et AI-assistendi kasutamine aitas paremini m\u00f5ista erinevate s\u00fcndmuste t\u00f6\u00f6tlemise ts\u00fcklite t\u00e4itmise ise\u00e4rasusi QEMU-s. <\/p>\n

M\u00e4rkimisv\u00e4\u00e4rne on see, et probleemi oli \u00fcsna raske avastada, kuna s\u00fcnteetilistes testides ei registreerita aeglustumist, kuna t\u00f5rke ilmnemine s\u00f5ltub s\u00fcndmuste t\u00f6\u00f6tlemise ts\u00fckli k\u00e4ivitamisest ppoll t\u00f5ttu muust tegevusest, ja s\u00fcnteetilised sisendi\/v\u00e4ljundi testid ei t\u00f6\u00f6tle saadud andmeid. Aeglustumine muutus m\u00e4rgatavamaks mitme usleep() kutsumise lisamisel andmete t\u00f6\u00f6tlemise simuleerimiseks. <\/p>\n

Enne parandamist seisundis olev s\u00fcsteem (idle): time sudo .\/iotest \/dev\/sda Tehtud 25,76 sekundi jooksul fish v\u00e4line usr aeg 6,19 millis 783,00 mikrosekundit 5,41 millis sys aeg 12,43 millis 642,00 mikrosekundit 11,79 millis <\/p>\n

P\u00e4rast parandamist seisundis olev s\u00fcsteem: time sudo .\/iotest \/dev\/sda Tehtud 1,30 sekundi jooksul fish v\u00e4line usr aeg 2,14 millis 0,14 millis 2,00 millis sys aeg 16,93 millis 1,16 millis 15,76 millis
\n
Allikas: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0419\u0435\u043d\u0441 \u042d\u043a\u0441\u0431\u043e (Jens Axboe), \u0441\u043e\u0437\u0434\u0430\u0442\u0435\u043b\u044c io_uring \u0438 \u043f\u043b\u0430\u043d\u0438\u0440\u043e\u0432\u0449\u0438\u043a\u043e\u0432 \u0432\u0432\u043e\u0434\u0430\/\u0432\u044b\u0432\u043e\u0434\u0430 CFQ, Deadline \u0438 Noop, \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0438\u043b \u0434\u043b\u044f \u0432\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u044f \u0432 \u043a\u043e\u0434\u043e\u0432\u0443\u044e \u0431\u0430\u0437\u0443 \u044d\u043c\u0443\u043b\u044f\u0442\u043e\u0440\u0430 QEMU \u043f\u0430\u0442\u0447, \u0432 50-80 \u0440\u0430\u0437 \u0441\u043e\u043a\u0440\u0430\u0449\u0430\u044e\u0449\u0438\u0439 \u0437\u0430\u0434\u0435\u0440\u0436\u043a\u0438 \u043f\u0440\u0438 \u0440\u0430\u0431\u043e\u0442\u0435 fdmon (file descriptor monitoring) \u0432 \u0440\u0435\u0436\u0438\u043c\u0435 «aio=io_uring» \u0438 \u043d\u0430\u0445\u043e\u0436\u0434\u0435\u043d\u0438\u0438 \u0441\u0438\u0441\u0442\u0435\u043c\u044b \u0432 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0438 \u043f\u0440\u043e\u0441\u0442\u043e\u044f (idle). \u041f\u0440\u043e\u0431\u043b\u0435\u043c\u0430 \u043f\u0440\u043e\u044f\u0432\u043b\u044f\u043b\u0430\u0441\u044c \u0438\u0437-\u0437\u0430 \u043f\u0435\u0440\u0435\u0432\u043e\u0434\u0430 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u0438 ppoll() \u0432 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0438 \u0441\u043d\u0430 \u0441 \u0442\u0430\u0439\u043c\u0430\u0443\u0442\u043e\u043c 499 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-161903","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47io_uringi arendaja tuvastas QEMU-s probleemi, mis aeglustas fdmoni idle-re\u017eiimis 50-80 korda | ProHoster","description":"Jens Axboe, io_uringi looja ja sisendi\/v\u00e4ljundi planeerijate CFQ, Deadline ja Noop autor, pakkus QEMU emulaatorikoodibaasi lisamiseks pat\u0161i, mis v\u00e4hendab fdmoni (file) latentsust 50-80 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