Faerstain, Bert wrote:
Does anyone know if I can increase the Direct-IO size on an xfs
filesystem running x86? I'm getting 256K (262144) as the maxsize for
DIO. I want at least 6 or 7 MB. Is this tied in some way to the 4K
pagesize on x86? this would still seem too small. Would looking into
hugepage kernel params help me somehow? what parameter can i change to
increase the DIO maxsize?
You cannot change it, but you can ignore it. It appears to be a
hardcoded constant in 2.6. If you submit a larger I/O it will
still accept it. This value originally represented the maximu
amount of memory which could be dma transferred in one go on
MIPS Irix hardware. On linux it does not really have meaning,
but the actual transfer size out to disk is somewhat of an
unknown - very dependent on hardware and other factors you
cannot control.
Probably the limit should be bumped - or the documentation
changed.
Steve
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