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Bug 1066570 (Cumulative_RX_TX_Statistics_VDSM) - [RFE] Report actual rx_byte instead of a false rxRate
Summary: [RFE] Report actual rx_byte instead of a false rxRate
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: Cumulative_RX_TX_Statistics_VDSM
Product: vdsm
Classification: oVirt
Component: RFEs
Version: ---
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified vote
Target Milestone: ovirt-3.6.0-rc
: 4.17.8
Assignee: Dan Kenigsberg
QA Contact: Meni Yakove
URL:
Whiteboard: network
Depends On: 1080494
Blocks: Cumulative_RX_TX_Statistics_VDSM_Engine
TreeView+ depends on / blocked
 
Reported: 2014-02-18 16:19 UTC by Dan Kenigsberg
Modified: 2016-02-10 19:16 UTC (History)
13 users (show)

Fixed In Version:
Doc Type: Enhancement
Doc Text:
Clone Of:
Environment:
Last Closed: 2015-11-27 07:49:14 UTC
oVirt Team: Network
rule-engine: ovirt-3.6.0+
ylavi: planning_ack+
rule-engine: devel_ack+
rule-engine: testing_ack+


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System ID Priority Status Summary Last Updated
oVirt gerrit 35061 None None None Never

Description Dan Kenigsberg 2014-02-18 16:19:26 UTC
Description of problem:
Vdsm (as well as layers above it) reports the rxRate for each network device. This number is calculated by dividing the bits transferred over the device per second, by the "speed" of the device. For nics, this speed is estimated based on the device driver. For vlan devices or nics that does not support speed (virtio, ib) it is faked as 1000mbps.

The speed is fake in the sense that on a host overloaded with multiple VMs, no vNIC has true 1000mbps. On the other hand, inter-VM communication can easily go above 100% of the virtio "speed".

In several cases (e.g. when calculating total VM traffic), Engine multiplies the two values to re-produce the actual values. Introducing meaningless numbers into the computation only to remove them later, is bound to cause trouble (e.g. https://bugzilla.redhat.com/show_bug.cgi?id=996678#c7 )

Vdsm reports "speed" and rxRate/txRate since ever, and it would continue to do so in oVirt-3.y.z. However, it's a piece of API we should get straight.

Comment 1 Dan Kenigsberg 2014-02-27 11:50:08 UTC
Actually, we'd better report the actual rx_byte and the sample time, and not the calculated rate. The actual rx_byte/tx_byte are important for accounting. The only problem in that is that Linux byte counters may reset once they pass their 64 bit maximum, and are harder to maintain during migration.

Comment 2 Lior Vernia 2014-12-17 10:12:16 UTC
Dan, please note the current patch doesn't include sampling times - we'd also want those reported, as you mentioned in Comment 1, to enable the engine to properly compute rate on its own, so in the future the reported rates could be dropped (speed would still be required, though).

Comment 3 Yaniv Lavi 2015-04-05 13:24:59 UTC
Please check how this change affects DWH collection.

Comment 4 Shirly Radco 2015-04-13 12:04:23 UTC
This is a part of the Cummulative_RX_TX_Statistics feature. Will discuss the issue with Lior.

Comment 5 Red Hat Bugzilla Rules Engine 2015-10-18 08:34:52 UTC
Bug tickets that are moved to testing must have target release set to make sure tester knows what to test. Please set the correct target release before moving to ON_QA.

Comment 6 Michael Burman 2015-11-05 08:06:02 UTC
Verified on -  3.6.0.3-0.1.el6 and vdsm-4.17.10.1-0.el7ev.noarch

Comment 7 Sandro Bonazzola 2015-11-27 07:49:14 UTC
Since oVirt 3.6.0 has been released, moving from verified to closed current release.


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