From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: bad O_DIRECT read and write performance with small block sizes
  with virtio
Date: Tue, 03 Aug 2010 17:44:37 +0300
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Cc: Stefan Hajnoczi <stefanha@gmail.com>, kvm@vger.kernel.org,
	Anthony Liguori <anthony@codemonkey.ws>
To: John Leach <john@brightbox.co.uk>
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  On 08/03/2010 05:40 PM, John Leach wrote:
>
> dd if=/dev/mapper/zero of=/dev/null bs=8k count=1000000 iflag=direct
> 8192000000 bytes (8.2 GB) copied, 3.46529 s, 2.4 GB/s
>
> dd if=/dev/mapper/zero of=/dev/null bs=8k count=1000000
> 8192000000 bytes (8.2 GB) copied, 5.5741 s, 1.5 GB/s
>
> dd is just using read.
>

What's /dev/mapper/zero?  A real volume or a zero target?

-- 
error compiling committee.c: too many arguments to function