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From Wido den Hollander <>
Subject Re: [MERGE] disk_io_throttling to MASTER
Date Fri, 31 May 2013 12:39:26 GMT
Hi Wei,

On 05/30/2013 06:03 PM, Wei ZHOU wrote:
> Hi,
> I would like to merge disk_io_throttling branch into master.
> If nobody object, I will merge into master in 48 hours.
> The purpose is :
> Virtual machines are running on the same storage device (local storage or
> share strage). Because of the rate limitation of device (such as iops), if
> one VM has large disk operation, it may affect the disk performance of
> other VMs running on the same storage device.
> It is neccesary to set the maximum rate and limit the disk I/O of VMs.

Looking at the code I see you make no difference between Read and Write 

Qemu and libvirt support setting both a different rate for Read and 
Write IOps which could benefit a lot of users.

It's also strange, in the polling side you collect both the Read and 
Write IOps, but on the throttling side you only go for a global value.

Write IOps are usually much more expensive then Read IOps, so it seems 
like a valid use-case where that an admin would set a lower value for 
write IOps vs Read IOps.

Since this only supports KVM at this point I think it would be of great 
value to at least have the mechanism in place to support both, 
implementing this later would be a lot of work.

If a hypervisor doesn't support setting different values for read and 
write you can always sum both up and set that as the total limit.

Can you explain why you implemented it this way?


> The feature includes:
> (1) set the maximum rate of VMs (in disk_offering, and global configuration)
> (2) change the maximum rate of VMs
> (3) limit the disk rate (total bps and iops)
> JIRA ticket:
> FS (I will update later) :
> Merge check list :-
> * Did you check the branch's RAT execution success?
> Yes
> * Are there new dependencies introduced?
> No
> * What automated testing (unit and integration) is included in the new
> feature?
> Unit tests are added.
> * What testing has been done to check for potential regressions?
> (1) set the bytes rate and IOPS rate on CloudStack UI.
> (2) VM operations, including
> deploy, stop, start, reboot, destroy, expunge. migrate, restore
> (3) Volume operations, including
> Attach, Detach
> To review the code, you can try
> git diff c30057635d04a2396f84c588127d7ebe42e503a7
> f2e5591b710d04cc86815044f5823e73a4a58944
> Best regards,
> Wei
> [1]
> [2] refs/heads/disk_io_throttling
> [3]<>(CLOUDSTACK-1301
> -     VM Disk I/O Throttling)

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