I see in the code setCacheMode for KVM is there - i'm not certain how to
invoke it to use writeback.

https://git-wip-us.apache.org/repos/asf?p=cloudstack.git&a=search&h=HEAD&st=grep&s=setCacheMode

On 6/6/16 7:26 AM, Vladimir Melnik wrote:
> Dear colleagues,
> 
> I've found why guest's storage performance was much less than host's 
> performance (the mistake was too stupid to tell about it, really).
> 
> But I'd like to ask one more question if you don't mind. :) I played with 
> various KVM options (cache, io and so on...) and now I can say that I got 
> most IOpS with cache=writeback. Tests are being performed with the fio 
> utility, here is the jobfile contents:
>       [readtest]
>       blocksize=4k
>       filename=/dev/vdb
>       rw=randread
>       direct=1
>       buffered=0
>       ioengine=libaio
>       iodepth=32
>       size=20%
> 
>       [writetest]
>       blocksize=4k
>       filename=/dev/vdb
>       rw=randwrite
>       direct=1
>       buffered=0
>       ioengine=libaio
>       iodepth=32
>       size=20%
> 
> Is there any way to make ACS run create KVM domains with cache=writeback 
> instead of cache=none without patching the source code?
> 
> Thank you!
> 

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