{"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\/hu\/blog\/news\/razrabotchik-io_uring-vyyavil-v-qemu-problemu-v-50-80-raz-zamedlyavshuyu-fdmon-v-rezhime-prostoya","title":{"rendered":"Az io_uring fejleszt\u0151je egy probl\u00e9m\u00e1t fedezett fel a QEMU-ban, amely a fdmon m\u0171k\u00f6d\u00e9s\u00e9t 50-80%-kal lass\u00edtotta le \u00fcresj\u00e1ratban.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Jens Axboe, az io_uring \u00e9s a CFQ, Deadline \u00e9s Noop I\/O \u00fctemez\u0151k l\u00e9trehoz\u00f3ja, javaslatot tett egy patch beilleszt\u00e9s\u00e9re a QEMU emul\u00e1tor forr\u00e1sk\u00f3dj\u00e1ba, amely 50-80-szor cs\u00f6kkenti a fdmon (file descriptor monitoring) k\u00e9sleltet\u00e9seit az «aio=io_uring» m\u00f3dban, amikor a rendszer t\u00e9tlen \u00e1llapotban van. <\/p>\n

A probl\u00e9ma abb\u00f3l ad\u00f3dott, hogy a ppoll() m\u0171veletet 499 ms-os id\u0151t\u00fallal alv\u00f3 \u00e1llapotba helyezt\u00e9k, annak ellen\u00e9re, hogy volt I\/O. A f\u0151 esem\u00e9nyfeldolgoz\u00e1si ciklus folytat\u00e1s\u00e1hoz, amelyet a ppoll() miatt felf\u00fcggesztettek, javasoltak egy foltot, amely a SQE (Submission Queue Entry) l\u00e9trehoz\u00f3 funkci\u00f3hoz hozz\u00e1adja az aio_notify() h\u00edv\u00e1st, hogy kihozza a ppoll()-t az alv\u00f3 \u00e1llapotb\u00f3l. <\/p>\n

A probl\u00e9ma io_uring regresszi\u00f3s tesztel\u00e9se sor\u00e1n mer\u00fclt fel virtu\u00e1lis g\u00e9pekben<\/a> k\u00fcl\u00f6nb\u00f6z\u0151 blokkeszk\u00f6z\u00f6kkel. Jens felh\u00edvta a figyelmet az AHCI\/SATA eszk\u00f6z\u00f6k «aio=io_uring» m\u00f3dban val\u00f3 haszn\u00e1lata sor\u00e1n tapasztalhat\u00f3 v\u00e9letlenszer\u0171 timeoutokra, m\u00edg a virtio-blk vagy nvme eszk\u00f6z\u00f6kkel v\u00e9gzett konfigur\u00e1ci\u00f3kban a tesztek mindig k\u00f6r\u00fclbel\u00fcl egy m\u00e1sodperc alatt befejez\u0151dtek. Megjegyzend\u0151, hogy a probl\u00e9ma minden blokk\u00e9sz\u00fcl\u00e9ket \u00e9rint, de az AHCI\/SATA eszk\u00f6z\u00f6k eset\u00e9ben a k\u00e9sleked\u00e9sek megjelen\u00e9se a MMIO haszn\u00e1lata miatt a legszembet\u0171n\u0151bb. <\/p>\n

Jens azt is le\u00edrta, hogy hogyan debuggolta a probl\u00e9m\u00e1t a Claude AI-asszisztens seg\u00edts\u00e9g\u00e9vel. Miut\u00e1n meghat\u00e1rozta a forgat\u00f3k\u00f6nyvet, amely reproduk\u00e1lja az id\u0151t\u00fall\u00e9p\u00e9s felt\u00e9teleit, \u00e1tadta a megl\u00e9v\u0151 hibakeres\u00e9si adatokat Claude-nak, hozz\u00e1f\u00e9r\u00e9st biztos\u00edtott a virtu\u00e1lis g\u00e9phez, \u00e9s felaj\u00e1nlotta, hogy meghat\u00e1rozz\u00e1k a felfedezett hiba val\u00f3sz\u00edn\u0171 okait. <\/p>\n

Claude ellen\u0151rizni akarta, hogy lassul-e a m\u0171k\u00f6d\u00e9s a virtio-blk eszk\u00f6z haszn\u00e1latakor, \u00e9s elind\u00edtotta vele a fejleszt\u0151 \u00e1ltal javasolt destrukt\u00edv forgat\u00f3k\u00f6nyvet, amely a probl\u00e9m\u00e1t szimul\u00e1lja. A teszt sor\u00e1n az els\u0151 128 MB tartalom t\u00f6rl\u00e9sre ker\u00fclt a blokk eszk\u00f6zb\u0151l (\/dev\/vda) egy virtu\u00e1lis g\u00e9pen. Ezt k\u00f6vet\u0151en Claude azt a k\u00f6vetkeztet\u00e9st vonta le, hogy a probl\u00e9ma nem a virtio-blkban van. Amikor Jens az AI-asszisztensnek jelezte a \/dev\/vda tartalm\u00e1nak t\u00f6rl\u00e9s\u00e9t, az azt v\u00e1laszolta: «Igen, megcsin\u00e1ltam», majd a helyre\u00e1ll\u00edt\u00e1si k\u00e9r\u00e9s ut\u00e1n helyre\u00e1ll\u00edtotta a virtu\u00e1lis lemez m\u0171k\u00f6d\u00e9s\u00e9t a \/dev\/vda-n. Megjegyzend\u0151, hogy az AI-asszisztens haszn\u00e1lata seg\u00edtett jobban meg\u00e9rteni a k\u00fcl\u00f6nb\u00f6z\u0151 esem\u00e9nykezel\u00e9si ciklusok v\u00e9grehajt\u00e1s\u00e1nak saj\u00e1toss\u00e1gait a QEMU-ban. <\/p>\n

\u00c9rdekes, hogy a probl\u00e9m\u00e1t el\u00e9g neh\u00e9z volt \u00e9szlelni, mivel a szintetikus tesztekben a lassul\u00e1s nem \u00e9szlelhet\u0151, mert a hib\u00e1k megjelen\u00e9s\u00e9t befoly\u00e1solja az esem\u00e9nykezel\u00e9si ciklus fel\u00e9leszt\u00e9se a ppoll miatt, m\u00e1s aktivit\u00e1s miatt, \u00e9s a szintetikus bemeneti\/kimeneti tesztek nem hajtj\u00e1k v\u00e9gre a kapott adatok feldolgoz\u00e1s\u00e1t. A lassul\u00e1s \u00e9szlelhet\u0151bb\u00e9 v\u00e1lt, amikor t\u00f6bb usleep() h\u00edv\u00e1st adtak hozz\u00e1 az adatok feldolgoz\u00e1s\u00e1nak szimul\u00e1l\u00e1s\u00e1ra. <\/p>\n

Jav\u00edt\u00e1s el\u0151tt a rendszer t\u00e9tlen \u00e1llapot\u00e1ban: time sudo .\\\/iotest \\\/dev\\\/sda V\u00e9grehajtva 25.76 secs fish k\u00fcls\u0151 usr time 6.19 millis 783.00 micros 5.41 millis sys time 12.43 millis 642.00 micros 11.79 millis <\/p>\n

Jav\u00edt\u00e1s ut\u00e1n a rendszer t\u00e9tlen \u00e1llapot\u00e1ban: time sudo .\\\/iotest \\\/dev\\\/sda V\u00e9grehajtva 1.30 secs fish k\u00fcls\u0151 usr time 2.14 millis 0.14 millis 2.00 millis sys time 16.93 millis 1.16 millis 15.76 millis
\n
Forr\u00e1s: 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\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\udd47Az io_uring fejleszt\u0151je felfedezett egy QEMU-probl\u00e9m\u00e1t, amely 50-80-szor lass\u00edtotta le az fdmon-t t\u00e9tlen \u00e1llapotban | ProHoster","description":"Jens Axboe, az io_uring \u00e9s a CFQ, Deadline \u00e9s Noop bemeneti\/kimeneti \u00fctemez\u0151k megalkot\u00f3ja, javasolta, hogy a QEMU emul\u00e1tor k\u00f3dalapj\u00e1ba beleker\u00fclj\u00f6n egy jav\u00edt\u00e1s, amely 50-80-szor cs\u00f6kkenti 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