Re: fio posixaio performance problem

[Shaohua Li]

2011/8/3 Gui Jianfeng <guijianfeng@xxxxxxxxxxxxxx>:
> Hi,
>
> I ran a fio test to simulate qemu-kvm io behaviour.
> When job number is greater than 2, IO performance is
> really bad.
>
> 1 thread: aggrb=15,129KB/s
> 4 thread: aggrb=1,049KB/s
>
> Kernel: lastest upstream
>
> Any idea?
>
> ---
> [global]
> runtime=30
> time_based=1
> size=1G
> group_reporting=1
> ioengine=posixaio
> exec_prerun='echo 3 > /proc/sys/vm/drop_caches'
> thread=1
>
> [kvmio-1]
> description=kvmio-1
> numjobs=4
> rw=write
> bs=4k
> direct=1
> filename=/mnt/sda4/1G.img
Hmm, the test runs always about 15M/s at my side regardless how many threads.
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