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tuto:linux:tunning_hdd

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tuto:linux:tunning_hdd [2013/06/25 20:46] roottuto:linux:tunning_hdd [2013/06/25 21:10] – [tuning cfq] root
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 https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/Performance_Tuning_Guide/index.html https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/Performance_Tuning_Guide/index.html
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 +http://fr.wikipedia.org/wiki/Completely_Fair_Queuing
  
   * **back_seek_max** : Backward seeks are typically bad for performance, as they can incur greater delays in repositioning the heads than forward seeks do. However, CFQ will still perform them, if they are small enough. This tunable controls the maximum distance in KB the I/O scheduler will allow backward seeks. The default is 16 KB.   * **back_seek_max** : Backward seeks are typically bad for performance, as they can incur greater delays in repositioning the heads than forward seeks do. However, CFQ will still perform them, if they are small enough. This tunable controls the maximum distance in KB the I/O scheduler will allow backward seeks. The default is 16 KB.
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   * **slice_idle** : This specifies how long CFQ should idle while waiting for further requests. The default value in Red Hat Enterprise Linux 6.1 and earlier is 8 ms. In Red Hat Enterprise Linux 6.2 and later, the default value is 0. The zero value improves the throughput of external RAID storage by removing all idling at the queue and service tree level. However, a zero value can degrade throughput on internal non-RAID storage, because it increases the overall number of seeks. For non-RAID storage, we recommend a slice_idle value that is greater than 0.   * **slice_idle** : This specifies how long CFQ should idle while waiting for further requests. The default value in Red Hat Enterprise Linux 6.1 and earlier is 8 ms. In Red Hat Enterprise Linux 6.2 and later, the default value is 0. The zero value improves the throughput of external RAID storage by removing all idling at the queue and service tree level. However, a zero value can degrade throughput on internal non-RAID storage, because it increases the overall number of seeks. For non-RAID storage, we recommend a slice_idle value that is greater than 0.
   * **slice_sync** : This tunable dictates the time slice allotted to a process issuing synchronous (read or direct write) I/O. The default is 100 ms.   * **slice_sync** : This tunable dictates the time slice allotted to a process issuing synchronous (read or direct write) I/O. The default is 100 ms.
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 ===== tuning deadline ===== ===== tuning deadline =====
  
tuto/linux/tunning_hdd.txt · Dernière modification : 2016/10/27 21:15 de root