Re: DM-Cache Writeback & Direct IO?

[Christoph Nelles <evilazrael@xxxxxxxxxxxxx>]

Hi Leonardo,

I am aware that sequential IO is routed directly to the backing device. And I also played with the parameters like sequential_threshold and the write_promote_adjustment introduced in 3.14.
To test this i ran ./fio --name=test --filename=/dev/mapper/dmcache  --rw=randwrite  --filesize=16G  --bs=64k --ioengine=libaio --direct=1 --iodepth=1000 in a endless loop.

Regards

Christoph


Am 08.07.2015 um 19:55 schrieb Leonardo Santos:

Are you using sequential or random workload? 

It's important, since DMCache bypasses sequential I/O based on theshold.

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