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Re: [Qemu-devel] qemu disk use writeback don't take effect in centos 7.2
From: |
Paul Schlacter |
Subject: |
Re: [Qemu-devel] qemu disk use writeback don't take effect in centos 7.2 1511 |
Date: |
Wed, 1 Nov 2017 20:03:41 +0800 |
Hi David:
yes, with the same qemu, centos 7.2 guest cache is writeback and
none, the disk io almost, writeback feeling no effect.
but 7.1/7.3/7.4 cache is writeback was significantly faster than
none model
On Wed, Nov 1, 2017 at 8:02 PM, Paul Schlacter <address@hidden> wrote:
> Hi David:
> yes, with the same qemu, centos 7.2 guest cache is writeback and
> none, the disk io almost, writeback feeling no effect.
> but 7.1/7.3/7.4 cache is writeback was significantly faster than
> none model
>
> On Wed, Nov 1, 2017 at 5:45 PM, Dr. David Alan Gilbert <
> address@hidden> wrote:
>
>> * Paul Schlacter (address@hidden) wrote:
>> > qemu version: 2.9.0
>> > image: centos 7.2 1511 raw
>> > cache mode: writeback
>> >
>> >
>> > In centos7.2 time, the use of writeback and none, the result of dd disk
>> is
>> > the same io, no change
>> >
>> > But I replaced centos7.1 centos7.3 centos7.4 when writeback was
>> > significantly faster than none
>> >
>> > Would like to ask what is going on, how to solve ?
>>
>> Hi Paul,
>> Can you just clarify your setup please; do you mean that
>> with the same qemu setup but a 7.2 guest rather than a 7.1/7.3 guest
>> the behaviour changes?
>>
>> Dave
>>
>> --
>> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>>
>
>