[Engine-devel] Updates in VdsUpdateRuntimeInfo

[Itamar Heim]

On 06/12/2013 09:41 AM, Barak Azulay wrote:
>
>
> ----- Original Message -----
>> From: "Itamar Heim" <iheim at redhat.com>
>> To: "Liran Zelkha" <lzelkha at redhat.com>
>> Cc: "engine-devel" <engine-devel at ovirt.org>
>> Sent: Tuesday, June 11, 2013 4:00:21 PM
>> Subject: Re: [Engine-devel] Updates in VdsUpdateRuntimeInfo
>>
>> On 06/11/2013 03:26 PM, Liran Zelkha wrote:
>>> Hi all,
>>>
>>> I'm checking performance for VdsUpdateRunTimeInfo.
>>> Naturally, much of the performance surrounds database activity
>>> (getVmsRunningOnVds queries, updateDeviceRuntimeInfo, updateVmDynamic)
>>>
>>> Few questions:
>>> 1. I have implemented batch updates for procedure UpdateVmDeviceRuntimeInfo
>>> for improved performance.
>>> 2. Seems like the only parameters UpdateVmDeviceRuntimeInfo is getting are
>>> vm_id,vm_device_id,address and alias. Are those rapidly changing, or will
>>> it be beneficial to implement caching on those updates (to ensure
>>> not-required updates do not travel to the database).
>>
>> slowly changing, but how will you cover all flows changing these devices
>> to invalidate the cache (iiuc, this table is modified by engine when
>> adding devices to a VM as well?)
>
>
> I don't think that in the device run time info we need to invalidate once we add a device.
> This is a specific case where we actually get the information from the VDSM (addresses are received from libvirt)
> The commands IIRC are first send to VDSM and than update the runtime info only on changed info (we can also hash it),
> It may put the placeholder in the DB first but it still relies on the data received from VDSM.

if this table is only updated from vdsm to save it, i agree.
but isn't the engine also manipulating it?
wasn't there a request to be able to maybe edit the addresses some day?