[Engine-devel] Updates in VdsUpdateRuntimeInfo

[Liran Zelkha]

Batch updates for UpdateVmDeviceRuntimeInfo, UpdateVdsInterfaceStatistics and UpdateVdsDynamic.
All improved execution performance by about 60-80%.

On Jun 12, 2013, at 4:05 PM, Itamar Heim wrote:

> On 06/12/2013 04:03 PM, Liran Zelkha wrote:
>> Hi all,
>> 
>> Current status of VdsUpdateRuntimeInfo (please note - patch is not yet committed).
>> Initial UpdateRuntimeInfo performance wasted roughly 57% of CPU time on DB activity. Of that, about 25% of CPU time wasted on update behavior.
>> After modification (moving updates to batch update) UpdateRuntimeInfo performance wasted roughly 40% of CPU time on DB activity. And only 12% of that was wasted on update behavior.
> 
> which changes are in place for above?
>> 
>> My next task is to try and optimize the rest of overall database performance.
>> 
>> 
>> ----- Original Message -----
>> From: "Liran Zelkha" <liran.zelkha at gmail.com>
>> To: "Barak Azulay" <bazulay at redhat.com>
>> Cc: "engine-devel" <engine-devel at ovirt.org>
>> Sent: Wednesday, June 12, 2013 12:35:03 PM
>> Subject: Re: [Engine-devel] Updates in VdsUpdateRuntimeInfo
>> 
>> Hi guys,
>> 
>> I'm working hard on this. I'll send summary mail and findings later today.
>> 
>> On Jun 12, 2013, at 10:45 AM, Barak Azulay wrote:
>> 
>>> 
>>> 
>>> ----- Original Message -----
>>>> From: "Itamar Heim" <iheim at redhat.com>
>>>> To: "Barak Azulay" <bazulay at redhat.com>
>>>> Cc: "engine-devel" <engine-devel at ovirt.org>
>>>> Sent: Wednesday, June 12, 2013 10:09:09 AM
>>>> Subject: Re: [Engine-devel] Updates in VdsUpdateRuntimeInfo
>>>> 
>>>> 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?
>>> 
>>> Even if there was such a request, we still update when we receive the info from libvirt.
>>> 
>>> Anyway there are obviously a few improvements to be done before caching.
>>> - update only when info received from VDSM change (need to verify it is the practice here)
>>> - do batch update for the new updated data received.
>>> - do the hashing (of vm device runtime info) on VDSM for the data , and update only when hash changes
>>> - caching ...
>>> 
>>> Barak
>>> 
>>> 
>>> 
>>>> 
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>>>> 
>>>> 
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