Re: [Qemu-devel] [PATCH] migration/block: Avoid involve into blk_drain too frequently

[858585 jemmy <jemmy858585@gmail.com>]

On Wed, Mar 15, 2017 at 10:57 AM, Fam Zheng <famz@redhat.com> wrote:
> On Wed, 03/15 10:28, 858585 jemmy wrote:
>> On Tue, Mar 14, 2017 at 11:12 PM, Eric Blake <eblake@redhat.com> wrote:
>> > On 03/14/2017 02:57 AM, jemmy858585@gmail.com wrote:
>> >> From: Lidong Chen <jemmy858585@gmail.com>
>> >>
>> >> Increase bmds->cur_dirty after submit io, so reduce the frequency involve into blk_drain, and improve the performance obviously when block migration.
>> >
>> > Long line; please wrap your commit messages, preferably around 70 bytes
>> > since 'git log' displays them indented, and it is still nice to read
>> > them in an 80-column window.
>> >
>> > Do you have benchmark numbers to prove the impact of this patch, or even
>> > a formula for reproducing the benchmark testing?
>> >
>>
>> the test result is base on current git master version.
>>
>> the xml of guest os:
>>     <disk type='file' device='disk'>
>>       <driver name='qemu' type='qcow2' cache='none'/>
>>       <source file='/instanceimage/ab3ba978-c7a3-463d-a1d0-48649fb7df00/ab3ba978-c7a3-463d-a1d0-48649fb7df00_vda.qcow2'/>
>>       <target dev='vda' bus='virtio'/>
>>       <alias name='virtio-disk0'/>
>>       <address type='pci' domain='0x0000' bus='0x00' slot='0x04'
>> function='0x0'/>
>>     </disk>
>>     <disk type='block' device='disk'>
>>       <driver name='qemu' type='raw' cache='none' io='native'/>
>>       <source dev='/dev/domu/ab3ba978-c7a3-463d-a1d0-48649fb7df00_vdb'/>
>>       <target dev='vdb' bus='virtio'/>
>>       <alias name='virtio-disk1'/>
>>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
>> function='0x0'/>
>>     </disk>
>>
>> i used fio running in guest os.  and the context of  fio configuration is below:
>> [randwrite]
>> ioengine=libaio
>> iodepth=128
>> bs=512
>> filename=/dev/vdb
>> rw=randwrite
>> direct=1
>>
>> when the vm is not durning migrate, the iops is about 10.7K.
>>
>> then i used this command to start migrate virtual machine.
>>
>> virsh migrate-setspeed ab3ba978-c7a3-463d-a1d0-48649fb7df00 1000
>> virsh migrate --live ab3ba978-c7a3-463d-a1d0-48649fb7df00
>> --copy-storage-inc qemu+ssh://10.59.163.38/system
>>
>> before apply this patch, during the block dirty save phase, the iops
>> in guest os is  only 4.0K, the migrate speed is about 505856 rsec/s.
>> after apply this patch, during the block dirty save phase, the iops in
>> guest os is is 9.5K. the migrate speed is about 855756 rsec/s.
>
> Thanks, please include these numbers in the commit message too.
OK, i will.
>
> Fam