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Date: Mon, 06 Jun 2016 17:58:47 -0700
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To: users@cloudstack.apache.org
Subject: Re: Storage Performance
References: <20160605160613.GA31486@shagomer.uplink.tucha13.net> <000201d1bf4c$789c3d60$69d4b820$@gmail.com> <20160605165036.GA7646@shagomer.uplink.tucha13.net> <CAPAyWNbSwMVAbFKRava84kq67Wx0WNiZHeTQYycwVDWiQeT+8Q@mail.gmail.com> <20160605170643.GB7646@shagomer.uplink.tucha13.net> <20160606142604.GC7646@shagomer.uplink.tucha13.net>
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archived-at: Tue, 07 Jun 2016 00:58:56 -0000

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!
>