The Trickle-Down Effect: Web Caching and Server Request ...


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request stream CDN servers clients

Internet

proxy caches

hosting network surrogate caches

request distributor

server cluster


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URL request stream SURGE or

trace input

server server server

LRU cache simulation request distribution (URLHASH or RANDOM)

server N server simulation


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6

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10

Zipf 0.6, no cache Zipf 0.6, 32MB front−end cache Zipf 0.6, 64MB front−end cache Zipf 0.6, 128MB front−end cache

5

5

10

10

4

4

10

References

References

10

3

10

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1

1

10

10

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3

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2

2

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0

1

10

2

3

10

10

4

10

5

10

Object rank

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2

3

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3. EXPERIMENTAL RESULTS

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5

10

Object rank

 ÇD-£º”pR;•g•gGG-½~F~ KÃ\JQN¾IÇR5Î4 š~ Ç£a V›oš—ÏD-•g¼TG-׺½~Uyš}ʒ£›l½\šQDZD?½~ ÈQ›%IKG£a•ašH ÇG?£ºR£oNAÊSÎ4GÊsš~šQUËUMU’”˜U’”˜U’Ê’U’£ʒ£a V V› ÀqUyœ*F~D-U’›l•a›U˽TÐcG•aIVD-IK›Ì F~ VFMD-È~£ašQFQUÊyUSÊSJ;GÊs VšQFUË£aUyš~ÀqUoUyFÅͺâBIVUy¡›l› £lD-•gЯG-£aÊyU’#U FM:=£a Ç£ašH›GFMœ*ЯDZD-›z• ££a½\š~D-\U ½~d&ÈQIًáG?•,è DZŒ n%¼…×z£lUy•gÊsG-£aÊy›UZœ*ÑQU’ V¿…›l›Ì ½~ VF5IKG£a Kš~FQU VF~œ*Ï* K£a›lš~›BU˛z£l›l•aœ0UyG-GœóIKIVU’• VF—F…æµÈ~œÉ VÏZ¼\ÈT•aUsU• D-ò…ÐON •aU’ЯU’•aUyF~ʒUy›£aDo£aš~U’›lU%D-¼T׺Uyʒ£a› Î4–TÈQš~½~Uɽ\ KD-F›l£aUtÈQ£a V£ašH VD-G?£OF¾•a¼\USÒUyšQÈ~ KUyF~›zJp£a›µ£a£ašQDEUUSG-£l•aÊg VšÉÊgÃTD-IV¼TU’׺ÌiJTUyʒD?£@ G?F;•aU4U’”˜UyÀqUyUyʒFQ£!IÇR% K›%JQG V›!›z£lа•aDZ V¼~IVIVÈQDS £aUy›yJ N £a VD-FoD VÐ £a– Û š~IVUBI  K›+ VGF~G½QÊyЯÈQG-È~£=ÊgFQš~£lʒU5•g£aG- VDZDʒzÐF—UZх—}DG-еF~JQ£aJ Vš~›z£a£aU!šH VF~ VG?FQÊs£A½~£* ÇÈQ£=DZ£+£g¼…G-JT×zÃZUy V›zÊsUy£l£a›e•a›y K–ÕNÕ¼QÈQ•aÎ4£aUy VšQ҅DZU5ÈQFQUy›+U’›z¿TG-£a›@½\FHUyJ0D-ÊsÐ\£a£a£aš~USš~J,UËU4ÊSÀZ£lG•gGÊsGIKÈQšQÊyUUU ›l@Ä  8– 7yUZ VÑQ›É¼~D-ÈTF£AÂ4£aš~UU*IKUyD-G?•gÀZJTU!U’•oG-›lD KJTÐËUìS#è£aš~˜0UаD҅•ÈQUy£a›zšQ£aUÚ VDZFÅìSëZD-ë-Ѝéš~ͺDSâB¡ £aD%£l•gÊyG-DZÊyœ*U*½Q ÈQ Ç£a£aU+šÖ V£SG N •a£aòqU’š~ê-Я V¡—U’›O•aÏ-âÕUy KF~ÀZÊSʒUyGUy›O›%Ês£ašQš~£aUZšQU4N ÆÉU*½TÎ4DZ•aDZ¼…š~¼H×zU+UyGÊs½Q¼~£%•a VIVD- Ç £º¼HR ÇG-£a¼Qš,£ašH VIK½\G? Ç£i£@D-Ro½~GE£aÈ~•ašHIKU’G?G?а•a£4Us V•a£iF~UyRpD-F~F~Êy•gG-U4U+F~£aD-ÃxDEЭ£aDZM+š~¼… K\U ×z›ÅUy–åÊsÄza£ ì•aM­™xUyœ*҅K-ÈQ VL«›lUyÆ›l›zšaUy£a›› :  VD-FÐ@G%£ašQ•aUU’аÊyU’G-•aÊgU’š~F~UoÊyU!G?£aЯ£aDoU’•%D-¼TG׺FUyBR ʒ£\–äMt V•aF5Usа£aU’šQ•aUyU!FQœ*ÊyUy V›y›lN› ›zÎ4£lš…•aUSÈ~G-›œž£ašQ V›œU›$½TL•aDZ‹]¼~K-G-¼~LlÄz Vì|IV Ç£º™ R K-L«Æ ša:£ašQ V›ËÏZ VÀqUy›!£ašQUɽQ•aD-¼HG¼~ VIV V£iRp£ašHG£ËG-FRpÏZ VÀqUyFUyIVUyœ*UyF£ËDÐ £aG-š~F%UE VF •aU’Û аF~U’ Ç•a£aU’UtF~•aÊyUSUÒœ*ÈQUy V›z›l£O›lUy›z› £l•a VUSFMGœ£aš~UË K›=ÊyGBG-Êg•aš~U’ЯUZU’N •aUyF~ʒU4£aDED-¼T׺UyʒW£ M˜G-F~J£aš~G£ æµØ\ K V½TÏZÈTЕadžU,‹ú›lè,š~Œ DSî; G-›ÚF~JG}–›lÊSG-‹öIVUSJåìSè!½~ŸZIVNÕD£—Î4D-šQQÐ U5› ÏL •gG-‹½~šÖK L ›lÄzš~fì DS™} ›oK £aL ƚ~šäG£oаD- Ç£*•Ú VG › £a½\š~USU+G?•Éœ* VD…FJQ£aUsš~•gGU0£aUyœ*IÇR0 V›l½\›DZ›z½Q£l•aÈ~USIKG-G{œ•4DZ:=¼…£a×zšQUyUyʒ›l£aU0›4£a¼\š~UyGÊy£ DZœ*G?•aU*U£aœ*šQD-U*›z£4œ*IVDZ VÃq›z£UyIÇR*½\DZ£a½~DÉÈQGIK½QG•Ì DZÊSG¼…È~×zU’›lʒU£a›4£ašQ VF*U½Q£aš~•aDZU ¼~Û G-IǼQ£aU’ KIV•a ÇUS£ºR—J0JQD-ÐA V›zG*£l•a VЯ¼~D-ÈT•lÂ4£a VGDZ•gF~Jp›tÊSD-G-ЍÊg浚~ VUÏZÈQœ*•aUE K›l›%òTN@ÄzœìÎ4™{šQ V›4K L  V›AÆ š ¼\U’ V›Ì À-G-F~ V›lšQ KFQÏZIÇR0›lœ0G-IVIHЯD-•+½\DZ½QÈ~IKG•BD-¼T׺Uyʒ£a›yÑT£aš…È~›tЯU’Âå•aUSÒÈ~Uy›z£a›t£aD

1

0.9

0.9

0.8

0.8

0.7

0.7

Object hit ratio

Object hit ratio

1

0.6

0.5

0.4

0.3 32MB front−end cache 64 MB front−end cache 128 MB front−end cache

0.2

ÿ

0.5

0.4

0.3

0.1

0.6

0

500

1000

1500

0.2

2000

2500

3000

3500

4000

0.1

4500

32MB front−end cache 64 MB front−end cache 128 MB front−end cache 0

500

1000

1500

2000

Object rank

2500

3000

3500

4000

4500

Object rank


- X  i¡f+R~.!ii ]2‚%'.ƒ¢!Y#…e+4^+~#) €^2¢]2RUVZ #-5 u R&1,%'.ˆ ‚  UV¢2Y %'-S‰&Y4R/$,$2F. #BŠ0$dx‹ Œ n,†$p-/.ˆ £  UV^2Y`%‡ /SŽ$ X‘.’f“¤ #-5

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250

References in cache miss stream

1998 IBM Trace Miss stream PDF

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3.2 Load Balancing

200

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1

10

2

10

3

10

4

10

5

10

Original object rank before caching (popularity)


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10

0.7

10

0.7 − no front−end cache − url hashing 0.7 − 32 MB front−end cache − url hashing 0.7 − 64 MB front−end cache − url hashing 0.7 − 128 MB front−end cache − url hashing 0.7 − 64 MB front−end cache − random switching 0.8 − no front−end cache − url hashing 0.8 − 64 MB front−end cache − url hashing

0.6

No Front End Cache 32MB Front End Cache 64MB Front End Cache 128MB Front End Cache

9

10

8

10

0.5

Bytes transferred

Load skew

7

0.4

0.3

10

6

10

5

10

4

10

0.2 3

10

0.1

2

10

1

10

0 4

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8

12

16

Number of back−end servers

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0.7 No front−end cache 32MB front−end cache 64MB front−end cache 128MB front−end cache 256MB front−end cache Infinite front−end cache

Load skew

0.5

0.4

0.3

0.2

0.1

0

4

8

16

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1

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2

10

3

10

4

10

5

10

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0.6

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