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Re: [Qemu-devel] Greate difference of disk I/O performance for guest on
From: |
cauchy-love |
Subject: |
Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS. |
Date: |
Fri, 19 Jun 2015 09:03:32 +0800 (CST) |
I have tried your qemu cammand line but got no luck (the embedded os have no
virtio support but this is not the problem i think). The problem probably lies
in the host kernel version as it is the only difference for my tests. I traced
the guest kernel and found the ATA drivers always used non-DMA mode (CentOS 7
and CentOS 6.5 are the same at this point).
Yi
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在 2015-06-16 21:05:39,"Stefan Hajnoczi" <address@hidden> 写道:
>On Mon, Jun 15, 2015 at 09:14:52PM +0800, cauchy-love wrote:
>> I am running a embedded OS on Qemu-2.3.0. However I found that the I/O
>> performance was quite different for different CentOS release (CentOS 6.5 and
>> CentOS 7.0). The CentOS 6.5 uses linux-2.6.32 while the CentOS 7.0 uses
>> linux-3.10.0. The I/O throughput (write) of the former (CentOS 6.5) is about
>> ten times of that on the latter (CentOS 7.0). All configurations are the
>> same except the kernel version. And the command line is as following:
>> # qemu-kvm -m 2G -smp 4 -enable-kvm -hda guest.img ...
>> The I/O throughput of the host is almost the same for these two different
>> kernels, as tested by Iozone tool. Actually, I found that the IO throughput
>> degraded significantly since the 3.4 or later kernel version. I also tried
>> different qemu versions such as qemu-1.5.3, qemu-2.1.3 but got no
>> improvements.
>
>Please post the iozone command-line you are using and the output.
>
>Your QEMU command-line uses the IDE storage controller, which is not
>optimized for performance. Usually virtio-blk is used when good
>performance is required:
>
> -drive if=virtio,cache=none,format=raw,aio=native,file=guest.img
>
>The guest OS needs virtio-blk device drivers in order for this to work.
>
>Stefan
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- [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., cauchy-love, 2015/06/15
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., Stefan Hajnoczi, 2015/06/16
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., cauchy-love, 2015/06/18
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS.,
cauchy-love <=
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., Paolo Bonzini, 2015/06/19
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., cauchy-love, 2015/06/22
- Message not available
- Message not available
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., cauchy-love, 2015/06/24
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., Paolo Bonzini, 2015/06/24
- Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS., cauchy-love, 2015/06/24