Category Archives: hirunningspace

vfs.hirunningspace and disk write latency performance

A while ago I increased the default value for the vfs.hirunningspace tunable - which greatly helps with performance when the disk system supports tagged queueing (e.g. NCQ), allowing many more requests to be offloaded into the controller and/or the drive(s). But deep queues bring their own problems, especially in pathological cases.

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