{"id":105185,"date":"2022-09-27T21:36:41","date_gmt":"2022-09-27T19:36:41","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/v-yadre-linux-najdena-zabytaya-zaplata-vliyayushhaya-na-proizvoditelnost-cpu-amd"},"modified":"2022-09-27T21:36:41","modified_gmt":"2022-09-27T19:36:41","slug":"v-yadre-linux-najdena-zabytaya-zaplata-vliyayushhaya-na-proizvoditelnost-cpu-amd","status":"publish","type":"post","link":"https:\/\/prohoster.info\/it\/blog\/news\/v-yadre-linux-najdena-zabytaya-zaplata-vliyayushhaya-na-proizvoditelnost-cpu-amd","title":{"rendered":"A forgotten patch affecting AMD CPU performance has been found in the Linux kernel.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Nel kernel Linux 6.0, il cui rilascio \u00e8 previsto per luned\u00ec prossimo, \u00e8 stata adottata una modifica che risolve i problemi di prestazioni dei sistemi basati su processori AMD Zen. La causa del calo delle prestazioni \u00e8 stato un codice aggiunto 20 anni fa per aggirare un problema hardware in alcuni chipset. Il problema hardware \u00e8 stato da tempo risolto e non si manifesta nei chipset attuali, ma il vecchio workaround \u00e8 stato dimenticato ed \u00e8 diventato una fonte di diminuzione delle prestazioni sui sistemi con i moderni CPU AMD. Le nuove sistemi con CPU Intel non sono interessati dal vecchio workaround, poich\u00e9 in esse l'accesso all'ACPI avviene tramite un driver separato intel_idle, anzich\u00e9 attraverso il driver comune processor_idle. <\/p>\n

Il workaround \u00e8 stato aggiunto al kernel nel marzo 2002 per bloccare l'emergere di un errore nei chipset, legato alla mancanza di un corretto stato di inattivit\u00e0 (idle) a causa di un ritardo nel trattamento del segnale STPCLK#. Per aggirare il problema nell'implementazione dell'ACPI, \u00e8 stata aggiunta un'istruzione WAIT che rallentava il processore per consentire al chipset di passare correttamente allo stato di inattivit\u00e0. Durante il profiling utilizzando le istruzioni IBS (Instruction-Based Sampling) sui processori AMD Zen3, \u00e8 emerso che il processore trascorre una quantit\u00e0 significativa di tempo eseguendo un fill, che porta a una scorretta interpretazione dello stato di carico del processore e all'impostazione di modalit\u00e0 di sonno pi\u00f9 profonde (C-State) da parte del gestore cpuidle. <\/p>\n

Questo comportamento si riflette in una diminuzione delle prestazioni sotto carichi in cui alternano frequentemente stati di inattivit\u00e0 (idle) e attivit\u00e0 (busy). Ad esempio, utilizzando una patch che disabilita il workaround, i punteggi medi del test tbench aumentano da 32191 MB\/s a 33805 MB\/s.
\n
Fonte: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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\u0431\u044b\u043b \u0437\u0430\u0431\u044b\u0442 \u0438 \u0441\u0442\u0430\u043b […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-105185","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\udd47Un vecchio fix trovato nel kernel Linux influisce sulle prestazioni dei CPU AMD | ProHoster","description":"Nel kernel Linux 6.0, il cui rilascio \u00e8 previsto per luned\u00ec prossimo, \u00e8 stato apportato un cambiamento che risolve i problemi di prestazioni dei sistemi basati su processori AMD 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