AMD yakaburitsa chirevo chekuongorora kuchengetedzeka kwePSF (Predictive Store Forwarding) tekinoroji yekuvandudza yakaitwa muZen 3 series processors. Chidzidzo ichi chakasimbisa kushanda kweSpecter-STL (Specter-v4) nzira yekurwisa, yakaonekwa muna Chivabvu 2018, kusvika. PSF tekinoroji, asi mukuita, hapana kodhi templates inokwanisa kutungamira mukurwiswa isati yawanikwa uye njodzi yese inoongororwa seisina kukosha.
Ngatiyeukei kuti Specter-v4 (Speculative Store Bypass) kurwiswa kwakavakirwa pakudzoreredza dhata rakagara muprocessor cache mushure mekurasa mhedzisiro yekufungidzira mashandiro ekuita kana uchigadzira kushandura kunyora uye kuverenga mashandiro uchishandisa isina kunanga kero. Kana kuvhiyiwa kwekuverenga kuchitevera basa rekunyora (semuenzaniso, mov [rbx + rcx], 0x0; mov rax, [rdx + rsi]), kubviswa kwekero yekuverenga kunogona kutozivikanwa nekuda kwekuita kwakafanana kuri kuitwa (kuverenga mashandiro ari inoitwa kakawanda uye kuverenga kunogona kuitwa kubva kucache) uye processor inogona kufungidzira kuverenga isati yanyora pasina kumirira kuti indirection yekunyora iverengerwe.
Ichi chinobvumira murairo wekuverenga kuti uwane kukosha kwekare pane imwe kero apo kushanda kwechitoro kusati kwapera. Kana paine chikanganiso chekufembera, iyo isina kubudirira yekufungidzira kushanda icharaswa, asi mitezo yekuitwa kwayo icharamba iri mu processor cache uye inogona kutorwa neimwe yenzira dzekuona zviri mukati mecache zvichibva pakuongororwa kwekuchinja kwekuwana. nguva yekuchengeta uye isina kuvharwa data.
Yakawedzerwa ku AMD Zen 3 processors, PSF inokwidziridza STLF (Chitoro-Ku-Kutakura-Kutumira), iyo inoita mabasa ekuverenga nekufungidzira nekufanotaura hukama pakati pekuverenga nekunyora mashandiro. Paunenge uchishandisa yekirasi STLF, processor inoita "mutoro" mashandiro pane iyo data yakananga mberi kubva kune yapfuura "chitoro" kuraira, pasina kumirira kuti mhedzisiro inyorwe kundangariro, asi kuve nechokwadi chekuti kero dzinoshandiswa mu "mutoro" uye "chitoro" mirairo mechi. Iyo PSF optimization inoita kuti kero yekutarisa kuve yekufungidzira uye inoita "mutoro" mashandiro ekero isati yaverengerwa kana chitoro / mutoro vaviri vachibiridzira kero imwe chete yakamboitwa. Kana kufanotaura kukatadza, nyika inodzoserwa kumashure, asi iyo data inoramba iri mu cache.
Kurwiswa kwePSF kunogoneka chete mukati meiyo nhanho imwe yeropafadzo, inovhara chete ikozvino maitiro mamiriro uye inovharwa nekero nzvimbo yekuzviparadzanisa nzira kana hardware sandbox masisitimu. Mune ino kesi, software sandboxing nzira mumatanho anogona kukanganiswa nedambudziko. Kurwiswa kwacho kunoisa kutyisidzira kune masisitimu akadai sebrowser, kodhi kuuraya chaiyo muchina, uye maJIT anoita yechitatu-bato kodhi mukati meimwe maitiro (kurwiswa kunogona kubvumira isina kuvimbika sandboxed kodhi kuwana mukana kune imwe process data).
AMD yakapa nzira dzinoverengeka dzekudzima zvachose kana kusarudza kudzima PSF, asi yakapihwa njodzi isingaite kune mazhinji maapplication, yakakurudzira kuti optimization iyi isavharwe nekukasira. Kusarudza kuchengetedza maitiro anoparadzanisa avo vanoita kodhi isingavimbike, zvinokurudzirwa kudzima PSF nekuisa "SSBD" uye "PSFD" MSR bits, kusanganisira kune yega tambo. Mapeche akagadzirirwa iyo Linux kernel nekuitwa kwe "psfd" uye "nopsfd" yekuraira mutsara sarudzo inodzora kuti PSF inobatidzwa nekudzimwa sei.
Source: opennet.ru