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【続編】その ionice、ほんとに効いてますか?
Takamura Narimichi
September 12, 2014
Technology
1
760
【続編】その ionice、ほんとに効いてますか?
2014/09/12 社内勉強会の資料です。前回の資料の続編です。
Takamura Narimichi
September 12, 2014
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Transcript
ʲଓฤʳͦͷ IONICE ɺ ΄Μͱʹޮ͍ͯ·͔͢ʁ גࣜձࣾϋʔτϏʔπ @nari_ex ߴଜಓ
͓͞Β͍ ionice ҎԼͷ ̎݅Λຬͨͨ࣌͠ʹͪΌΜͱ ಈ͘ I/O Scheduler ͕ CFQ ಛఆͷI/Oॲཧ
Ωϟογϡ͞Ε͍ͯͳ͍ϑΝΠϧͷRead ಛघϑϥάͷཱͬͨ Write
ΜɺͳΜͰ(ɾɾ)ʁ
CFQ ͡Όͳ͍ͱޮ͔ͳ͍ཧ༝
VFS Χʔωϧۭؒ γεςϜίʔϧ Ϣʔβۭؒ ཧ σόΠε ϑΝΠϧγεςϜ σΟεΫΩϟογϡ ൚༻ϒϩοΫ ཧ
σόΠε ϓϩηε I/Oεέδϡʔϥ σόΠε υϥΠό σόΠε υϥΠό I/Oεέδϡʔϥ I/O ͷ֓೦ਤ
I/O εέδϡʔϥ֓ཁ I/O
I/O εέδϡʔϥͷ αϒΩϡʔʹ
݁: CFQ Ҏ֎ɺ༏ઌΛߟྀͯ͠ ࣮͞Εͯͳ͍
දతͳI/Oεέδϡʔϥ • NOOP • DEADLINE • CFQʢCompletely Fair Queuingʣ
• ཁٻΛσΟεύονΩϡʔʹಥͬࠐΉ͚ͩ • No Operation NOOP I/O εέδϡʔϥ
NOOP I/O εέδϡʔϥ I/O
શ෦ೖΓͷFIFOΩϡʔ͕͋Δ͚ͩ
• ReadͱWriteͰΩϡʔ͕ผ • Read ༏ઌ • ظݶʢdeadlineʣ͖Ωϡʔ͕ಛ • ظݶ͕Εͨཁٻ࠷༏ઌͰॲཧ͢Δ DEADLINE
I/O εέδϡʔϥ
DEADLINE I/O εέδϡʔϥ I/O
READ ͱ WRITE ͷΩϡʔ͕͋Δ͚ͩ
• ϓϩηε͝ͱʹαϒΩϡʔΛ༻ҙ • ༏ઌΛߟྀͯ͠Ωϡʔ͝ͱͷॲཧ࣌ؒΛܾఆ • ̍ͭͷαϒΩϡʔΛΞΫςΟϒΩϡʔͱͯ͠ɺͦͷ ΩϡʔͷཁٻΛॲཧ࣌ؒͷൣғͰॲཧ͢Δ • ॲཧ͕࣌ؒऴΘΔͱΞΫςΟϒΩϡʔ͕ΓସΘΔ CFQ
I/O εέδϡʔϥ
CFQ I/O εέδϡʔϥ ϓϩηε͝ͱʹΩϡʔ͕͋Δ I/O
…"
CFQ I/O εέδϡʔϥ I/O
…" ΞΫςΟϒʹͳͬͨΩϡʔʹ͋Δ ཁٻ͕ॲཧ͞ΕΔ ༏ઌϓϩηεͷαϒΩϡʔ ΞΫςΟϒʹͳ͔ͳ͔ͳΒͳ͍ && ͳ͙ͬͯ͢ʹελϯόΠʹͳΔ
ಛఆͷI/O͡Όͳ͍ͱޮ͔ͳ͍ཧ༝
σΟεΫΩϟογϡͷޮ͍ͨREAD ϓϩηεۭؒ σΟεΫΩϟογϡ ཧσόΠε σΟεΫΩϟογϡͷ σʔλΛฦ͢
σΟεΫΩϟογϡͷͳ͍READ ϓϩηεۭؒ σΟεΫΩϟογϡ ཧσόΠε
σΟεΫΩϟογϡͷͳ͍READ ϓϩηεۭؒ σΟεΫΩϟογϡ ཧσόΠε σΟεΫΩϟογϡ࡞ σΟεΫΩϟογϡͷ σʔλΛฦ͢
ී௨ͷWRITEʢԆ WRITEʣ ϓϩηεۭؒ σΟεΫΩϟογϡ ཧσόΠε ޙͰॻ͖ࠐΈ σΟεΫΩϟογϡʹ ίϐʔΛͯ͠ऴྃ
ී௨ͷWRITEʢԆ WRITEʣ ϓϩηεۭؒ σΟεΫΩϟογϡ ཧσόΠε ޙͰॻ͖ࠐΈ σΟεΫΩϟογϡʹ ίϐʔΛͯ͠ऴྃ ୭͕Δͷʁ
ఆظతʹLINUX Χʔωϧ͕ॻ͖ࠐΜͰ·͢ɻ ※͔ͩΒ IONICE ͕ޮ͔ͳ͍
ఆظతͳಉظॲཧ
ಛघͳϑϥάͷཱͬͨI/O ϓϩηεۭؒ σΟεΫΩϟογϡ ཧσόΠε ΩϟογϡΛܦ༝ͤͣ σόΠεʹಡΈॻ͖͢Δ
࣭ίʔφʔ