* 鍐呮牳寤虹珛濂藉唴鏍擱〉鐩綍欏佃〃鏁版嵁搴擄紝鍋囪鐗╃悊鍐呭瓨澶у皬涓?/span>len錛屽垯寤虹珛浜?/span>[3G--3G+len]::[0--len]榪欐牱鐨勮櫄鍦板潃vaddr鍜岀墿鐞嗗湴鍧paddr鐨勭嚎鎬у搴斿叧緋伙紱
* 鍐呮牳寤虹珛涓涓?/span>page鏁扮粍錛?/span>page鏁扮粍鍜岀墿鐞嗛〉闈㈢郴鍒楀畬鍏ㄦ槸綰挎у搴旓紝page鐢ㄦ潵綆＄悊璇ョ墿鐞嗛〉闈㈢姸鎬侊紝姣忎釜鐗╃悊欏甸潰鐨勮櫄鍦板潃淇濆瓨鍦?/span>page->virtual涓紱
* 鍐呮牳寤虹珛濂戒竴涓?/span>free_list錛屽皢娌℃湁浣跨敤鐨勭墿鐞嗛〉闈㈠搴旂殑page鏀懼叆鍏朵腑錛屽凡緇忎嬌鐢ㄧ殑灝變笉鐢ㄦ斁鍏ヤ簡錛?/span>
2. 鍐呮牳妯″潡鐢寵鍐呭瓨vaddr = get_free_pages(mask,order)錛?/span>
* 鍐呭瓨綆＄悊妯″潡浠?/span>free_list鎵懼埌涓涓?/span>page錛屽皢page->virtual浣滀負榪斿洖鍊鹼紝璇ヨ繑鍥炲煎氨鏄搴旂墿鐞嗛〉闈㈢殑铏氬湴鍧錛?/span>
* 灝?/span>page浠?/span>free_list涓劚紱伙紱
* 妯″潡浣跨敤璇ヨ櫄鎷熷湴鍧鎿嶄綔瀵瑰簲鐨勭墿鐞嗗唴瀛橈紱
3. 鍐呮牳妯″潡浣跨敤vaddr錛屼緥濡傛墽琛屾寚浠?/span>mov(eax, vaddr)錛?/span>
* CPU鑾峰緱vaddr榪欎釜铏氬湴鍧錛屽埄鐢ㄥ緩绔嬪ソ鐨勯〉鐩綍欏佃〃鏁版嵁搴擄紝鎵懼埌鍏跺搴旂殑鐗╃悊鍐呭瓨鍦板潃錛?/span>
* 灝?/span>eax鐨勫唴瀹瑰啓鍏?/span>vaddr瀵瑰簲鐨勭墿鐞嗗唴瀛樺湴鍧鍐咃紱
4. 鍐呮牳妯″潡閲婃斁鍐呭瓨free_pages(vaddr,order)錛?/span>
* 渚濇嵁vaddr鎵懼埌瀵瑰簲鐨?/span>page錛?/span>
* 灝嗚page鍔犲叆鍒?/span>free_list涓紱
5. 鐢ㄦ埛榪涚▼鐢寵鍐呭瓨vaddr = malloc(size)錛?/span>
* 鍐呭瓨綆＄悊妯″潡浠庣敤鎴瘋繘紼嬪唴瀛樼┖闂?/span>(0--3G)涓壘鍒頒竴鍧楄繕娌′嬌鐢ㄧ殑絀洪棿vm_area_struct(start--end)錛?/span>
* 闅忓悗灝嗗叾鎻掑叆鍒?/span>task->mm->mmap閾捐〃涓紱
6. 鐢ㄦ埛榪涚▼鍐欏叆vaddr(0-3G)錛屼緥濡傛墽琛屾寚浠?/span>mov(eax, vaddr)錛?/span>
* CPU鑾峰緱vaddr榪欎釜铏氬湴鍧錛岃铏氬湴鍧搴旇宸茬粡鐢?/span>glibc搴撹緗ソ浜嗭紝涓瀹氬湪3G涓涓嬬殑鏌愪釜鍖哄煙錛屾牴鎹?/span>CR3瀵勫瓨鍣ㄦ寚鍚戠殑current->pgd鏌ュ綋鍓嶈繘紼嬬殑欏電洰褰曢〉琛ㄦ暟鎹簱錛屽彂鐜拌vaddr瀵瑰簲鐨勯〉鐩綍琛ㄩ」涓?/span>0錛屾晠浜х敓寮傚父錛?/span>
* 鍦ㄥ紓甯稿鐞嗕腑錛屽彂鐜拌vaddr瀵瑰簲鐨?/span>vm_area_struct宸茬粡瀛樺湪錛屼負vaddr瀵瑰簲鐨勯〉鐩綍琛ㄩ」鍒嗛厤涓涓〉琛紱
* 闅忓悗浠?/span>free_list鎵懼埌涓涓?/span>page錛屽皢璇?/span>page瀵瑰簲鐨勭墿鐞嗛〉闈㈢墿鐞嗛鍦板潃璧嬬粰vaddr瀵瑰簲鐨勯〉琛ㄨ〃欏癸紝寰堟槑鏄撅紝姝ゆ椂鐨?/span>vaddr鍜?/span>paddr涓嶆槸綰挎у搴斿叧緋諱簡錛?/span>
* 灝?/span>page浠?/span>free_list涓劚紱伙紱
* 寮傚父澶勭悊榪斿洖錛?/span>
* CPU閲嶆柊鎵ц鍒氬垰鍙戠敓寮傚父鐨勬寚浠?/span>mov(eax, vaddr)錛?/span>
* CPU鑾峰緱vaddr榪欎釜铏氬湴鍧錛屾牴鎹?/span>CR3瀵勫瓨鍣ㄦ寚鍚戠殑current->pgd錛屽埄鐢ㄥ緩绔嬪ソ鐨勯〉鐩綍欏佃〃鏁版嵁搴擄紝鎵懼埌鍏跺搴旂殑鐗╃悊鍐呭瓨鍦板潃錛?/span>
* 灝?/span>eax鐨勫唴瀹瑰啓鍏?/span>vaddr瀵瑰簲鐨勭墿鐞嗗唴瀛樺湴鍧鍐咃紱
7. 鐢ㄦ埛榪涚▼閲婃斁鍐呭瓨vaddr錛?/span>free(vaddr)錛?/span>
* 鎵懼埌璇?/span>vaddr鎵鍦ㄧ殑vm_area_struct錛?/span>
* 鎵懼埌vm_area_struct:start--end瀵瑰簲鐨勬墍鏈夐〉鐩綍欏佃〃欏癸紝娓呯┖瀵瑰簲鐨勬墍鏈夐〉琛ㄩ」錛?/span>
* 閲婃斁榪欎簺欏佃〃欏規寚鍚戠墿鐞嗛〉闈㈡墍瀵瑰簲鐨?/span>page錛屽茍灝嗚繖浜?/span>page鍔犲叆鍒?/span>free_list闃熷垪涓紱
* 鏈夊繀瑕佽繕浼氭竻絀轟竴浜涢〉鐩綍琛ㄩ」錛屽茍閲婃斁榪欎簺欏電洰褰曡〃欏規寚鍚戠殑欏佃〃錛?/span>
* 浠?/span>task->mm->mmap閾句腑鍒犻櫎璇?/span>vm_area_struct騫墮噴鏀炬帀錛?/span>
緇煎悎璇存槑錛?/span>
* 鍙敤鐗╃悊鍐呭瓨灝辨槸free_list涓悇page瀵瑰簲鐨勭墿鐞嗗唴瀛橈紱
* 欏電洰褰曢〉琛ㄦ暟鎹簱鐨勪富瑕佺洰鐨勬槸涓?/span>CPU璁塊棶鐗╃悊鍐呭瓨鏃惰漿鎹?/span>vaddr-->paddr浣跨敤錛屽垎閰嶄互鍙婇噴鏀懼唴瀛樻椂涓嶄細鐢ㄥ埌錛屼絾鏄渶瑕佸唴鏍稿唴瀛樼鐞嗙郴緇熷湪鍚堥傛椂鏈轟負CPU寤虹珛濂借搴擄紱
* 瀵逛簬鐢ㄦ埛榪涚▼鍦?/span>6涓幏寰楃殑鐗╃悊欏甸潰錛屾湁涓や釜欏佃〃欏瑰搴旓紝涓涓氨鏄唴鏍擱〉鐩綍欏佃〃鏁版嵁搴撶殑鏌愪釜pte[i ]錛屼竴涓氨鏄綋鍓嶈繘紼嬪唴鏍擱〉鐩綍欏佃〃鏁版嵁搴撶殑鏌愪釜 pte[j]錛屼絾鏄彧鏈変竴涓?/span>page鍜屽叾瀵瑰簲銆傚鏋滄鏃惰皟搴﹀埌鍏朵粬榪涚▼錛屽叾浠栬繘紼嬬敵璇峰茍璁塊棶鏌愪釜鍐呭瓨錛屽垯涓嶄細娑夊強鍒拌鐗╃悊欏甸潰錛屽洜涓哄叾鍒嗛厤鏃墮鍏堣浠?/span> free_list涓壘涓涓?/span>page錛岃岃鐗╃悊欏甸潰瀵瑰簲鐨?/span>page宸茬粡浠?/span>free_list涓劚紱誨嚭鏉ヤ簡錛屽洜姝や笉瀛樺湪璇ョ墿鐞嗛〉闈㈣鍏朵粬榪涚▼鏀瑰啓鎿嶄綔鐨勬儏鍐點傚唴鏍鎬腑閫氳繃get_free_pages絳夋柟寮忚幏鍙栧唴瀛樻椂錛屼篃涓嶄細娑夊強鍒拌鐗╃悊欏甸潰錛屽師鐞嗗悓鍓嶆墍榪般?/span>
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1. 灝藉彲鑳戒笉瑕佸垱寤篻lobal reference鍜実lobal weak reference. 鍒涘緩榪欎袱綾誨紩鐢ㄧ殑JNI鎺ュ彛NewGlobalReference鍜孨ewGlobalWeakReference鍐呴儴瀹炵幇
鏈変竴涓攣銆傝繖涓攣浣垮緱鍦ㄥ澶勭悊鍣ㄤ笂鐨勫彲鎵╁睍鎬ч潪甯稿樊錛屽洜涓哄悇涓嚎紼嬮兘鍦ㄧ瓑寰呰繖涓攣銆傛墍浠ュ敖閲忎笉瑕佸湪native淇濆瓨java 瀵硅薄鐨勫紩鐢紝鎯呮効鍦ㄦ瘡嬈?/span>
JNI call鏃墮兘甯︾偣鍙傛暟銆傚綋鐒訛紝鍦╪ative淇濇寔java瀵硅薄鐨刲ocal reference鏄潪甯稿嵄闄╃殑錛岀粷瀵逛笉鑳介偅鏍峰共銆?/span>
2. 灝介噺涓嶈浣跨敤GetPrimitiveArrayCritical/ReleasePrimitiveArrayCritical鏉in浣廕ava鍐呭瓨銆侸VM鏈韓娌℃湁鎻愪緵浠諱綍鍙猵in浣忎竴鍧桱ava鍐呭瓨鑰屼笉褰?/span>
鍝岹C鐨勬搷浣滐紝鎵浠ヨ繖涓搷浣滄槸浼氶樆姝C榪涜鐨勩備綔涓鴻ˉ鍋匡紝ReleasePrimitiveArrayCritical浼氫駭鐢熶竴嬈￠殣寮忕殑GC璋冪敤銆傝繖鏍峰氨鍙兘鍑虹幇鍦ㄩ渶瑕丟C鐨勬椂
鍊欐棤娉旼C錛岃屽湪涓嶉渶瑕丟C鏃惰繘琛屾棤鎰忎箟GC鐨勬儏鍐點傚彟澶栵紝榪欎袱涓搷浣滅殑瀹炵幇涓湪鏌愪簺鎯呭喌涓嬩篃鍙兘瑙﹀彂閿併傝В鍐蟲柟娉曪細濡傛灉鏄皬鍧楀唴瀛樼殑璇濓紝鎯呮効浣?/span>
鐢℅et<Type>ArrayRegion鍜孲et<Type>ArrayRegion鏉ュ湪native鍜孞ava涔嬮棿澶嶅埗鍐呭瓨銆?/span>
3. 鍦↗ava appliation涓敖閲忎笉瑕佸垱寤簆hantom reference鎴栬卻oft reference銆傝繖浜況eference浼氭瀬澶х殑褰卞搷GC銆?/span>
鎴戜滑鍏堟潵璋堣皥JVM鐨凣C銆侴C鍒嗕負minor GC鍜宖ull GC銆侸ava鍐呭瓨鍒嗕負young鍜宱ld涓や唬銆傚湪young memory涓紝姣忎釜綰跨▼閮芥湁鑷繁鐨勫唴瀛樺垎閰嶅潡錛堜笉鍜屽叾瀹?/span>
綰跨▼鍏變韓錛夛紝鑰宱ld memory鏄敱鎵鏈夌嚎紼嬪叡浜殑銆俶inor GC鍙young memory浣淕C錛岃宖ull GC瀵規墍鏈夊唴瀛橀兘鍋欸C銆俶inor GC鏄彲浠ュ綰跨▼騫惰榪涜鐨?/span>
錛岃宖ull GC榛樿鍙兘鍗曠嚎紼嬫墽琛屻傛墍浠ワ紝涓嬈ull GC闇瑕佺殑鏃墮棿鍙互鏄痬inor GC鏄?0鍊嶄互涓婏紙鍙互鐢?verbose:gc瑙傚療錛夈傛墍浠ュ湪涓鑸簲鐢ㄤ腑錛?/span>
minor GC鐨勬鏁板簲璇ユ槸full GC鐨?0鍊嶅乏鍙蟲槸姣旇緝鐞嗘兂鐨勩俶inor GC浼氬皢鏃犳硶鏀墮泦鐨勫璞＄Щ鍔ㄥ埌old memory涓幓銆?/span>
minor GC涓嶄細瀵筽hantom reference鍜宻oft reference榪涜鏀墮泦錛屽彧鏈塮ull GC鎵嶄細銆傝繖鏍風殑闂灝辨槸澶ч噺鐨勮繖綾誨璞＄Н鑱氳搗鏉ワ紝浜х敓璁稿鐨勫唴瀛樺鍒躲?/p>
榪欐牱姣忔minor GC鍙兘灝卞熀鏈笂娌℃湁閲婃斁澶氬皯鍐呭瓨錛屼嬌寰梖ull GC灝變細琚綣佽Е鍙戙傚彲鑳藉嚭鐜癿inor GC鍜宖ull GC嬈℃暟1錛?鐨勬儏鍐碉紝鐢氳嚦鍏ㄦ槸full GC銆?/p>
榪欐牱錛屾棤璁烘槸鎬ц兘榪樻槸鍙墿灞曟ч兘鏄潪甯稿樊鐨勩?br />
weak reference鐨勫獎鍝嶅ソ鍍忓皬涓浜涳紝浣嗕篃搴旇灝介噺閬垮厤銆?/span>
鍦↗NI寮鍙戜腑錛屼嬌鐢ㄨ繖3縐峳eference鐨勪富瑕佺洰鐨勬槸淇濊瘉native璧勬簮鐨勯噴鏀俱傚洜涓簀ava瀵硅薄鐨刦inalize鏂規硶鏄笉淇濊瘉琚皟鐢ㄧ殑錛屾墍浠ュ繀欏葷敤榪欎簺
reference鏉ュ府鍔╁疄鐜皀ative璧勬簮閲婃斁銆備負浜嗛伩鍏嶄笂榪扮殑闂錛屼竴縐嶅彲琛岀殑鏂規硶鏄皢native璧勬簮serialize鎴愪竴鍧楀唴瀛橈紝鐒跺悗鏀懼埌java瀵硅薄涓繚瀛橈紝浠?/span>鑰岄伩鍏嶄嬌鐢ㄨ繖浜況eference銆?/span>
4. NIO鏄笉閿欑殑Java鍜宯ative涔嬮棿share memory鐨勬柟娉曘備絾瑕佹敞鎰忓畠鐨勬ц兘銆傞鍏堜竴瀹氳璁劇疆瀵筨ig endian榪樻槸little endian錛岄槻姝VM鍋氶澶栫殑
endian杞崲鍔ㄤ綔銆傚叾嬈℃槸鍦ㄥ惎鍔↗VM鏃朵竴瀹氳鍔犱笂-server閫夐」錛屽惁鍒檔io鎬ц兘浼氶潪甯稿樊銆傚湪-server mode涓嬶紝nio鎬ц兘澶ф姣攋ava鏁扮粍鎱?0%~50%.鍦?
client mode涓嬶紝鎬ц兘宸?鍊嶄互涓娿?/span>
5. 灝介噺涓嶈鍦↗NI鍘籲ew Java String瀵硅薄銆傝繖涓瘮鍦╦ava灞俷ew鎱㈠緢澶氥?/span>
6. 瀵筳ava澶у璞★紙姣旀柟璇存暟緇勶級錛屼竴瀹氳浠旂粏鐨則une浠栫殑澶у皬銆備竴鑸潵璇達紝灝忓璞″GC姣旇緝鍙嬪ソ銆傚洜涓哄璞″垎閰嶆椂鍏堢湅姣忎釜綰跨▼鑷繁鐨剏oung memory
錛屽鏋滄壘鐨勫埌瓚沖澶х殑鍐呭瓨鐨勮瘽錛屽氨鍒嗛厤銆傚惁鍒欏湪old memory涓垎閰嶃傚洜涓簅ld memory鏄痵hared錛屾墍浠ュ彲鑳芥湁閿佸紑閿銆傝屼笖old memory涓殑瀵硅薄鍙湁
full GC鎵嶈兘閲婃斁瀹冦傛墍浠ュ璞℃瘮杈冨皬鏄瘮杈冨ソ鐨勩侸VM鐨勫唴瀛樺垎閰嶇畻娉曟槸涓哄皬瀵硅薄浼樺寲榪囩殑錛屽ぇ閲忓皬瀵硅薄鐨勫垎閰嶆槸寰堥珮鏁堢殑錛屾墍浠ヤ笉鐢ㄦ曟妸澶у璞℃媶灝忋?/span>
鍦ㄦ煇浜涙儏鍐典笅錛屽鏋滅煡閬撳璞′細媧葷殑寰堜箙鐨勮瘽錛屽氨璁╁畠澶т竴鐐癸紝澧炲姞瀹冪洿鎺ュ垎閰嶅湪old memory涓殑姒傜巼銆傝繖鏍峰彲浠ヨ妭綰oung GC鎷瘋礉榪欎釜瀵硅薄鍒皁ld
memory涓殑寮閿銆?/p>
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