gnome-panel spins causing high cpu in Trusty 14.04

[Lakshminarayanan Seshadri]

Machine Make : Dell Inspiron 1440 , Intel® Core™2 Duo CPU T6600 @ 2.20GHz × 2 .
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Graphics support : Mobile Intel® GM45 Express Chipset .
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OS/Install : Fresh install of Ubuntu 14.04.3 desktop (kernel 3.19.0-26-generic) machine with "gnome-session flashback" installed.
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UI Session : "Gnome session with metacity" option login
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Issue : Moving cursor near Applications menu (next to Places) causes flickering in screen together with high CPU usage caused by "gnome-panel" process.
More Data: It appears that gnome-panel is spinning on a mutex causing high cpu usage .

[Lakshminarayanan Seshadri (lnarayanan-seshadri)]

pls see attached cpu sample from perf in kernel tools for the gnome-panel process spinning on a mutex cauing high cpu.

[Lakshminarayanan Seshadri (lnarayanan-seshadri)]

Not a big worry at moment but little annoying to see the simple gnome-session process i.e gnome-panel consuming high cpu momentarily each time when moved near "Applications" menu in top left on panel. i don't know any other details on the gnome package : gnome-session flashback which i came to know is equivalent of simple/classic gnome session found in Ubuntu 12.04 LTS which i was happily using.
So pls check the above data in bug and judge accordingly .
thx

[Dmitry Shachnev (mitya57)]

Hi,

First, you say that it's gnome-panel that uses CPU, then why did you file this bug against gnome-flashback (and not gnome-panel)?

Second, the perf output is not really helpful because these two functions are expectedly the most common called ones, and it's not strange that they are on top of the output.

[Lakshminarayanan Seshadri (lnarayanan-seshadri)]

Hi
1. Is the gnome-panel not brought in by gnome-session flashback package? My assumption was that on a fresh Ubuntu 14.04.3 install the gnome-panel was not present and one only gets standard Ubunty Unity default session choice. Only after installing the flashback package one got the gnome session(compiz,metacity) choices.
Pls mark the bug accordingly if you have more details/knowhow on it.

2. Also what other type of output do you need/expect, gdb backtrace ? i can try to attach them if i get to it soon.

thx

[Dmitry Shachnev (mitya57)]

Can you try with 15.04 (stable) or 15.10 (development) releases? There were lots of changes since 3.8, and this bug may be fixed there.

[Lakshminarayanan Seshadri (lnarayanan-seshadri)]

Trying to clear some space and see if i can test with above builds. But is it possible to get backports of those fixes for gnome-panel in 14.0.4.3 LTS release?

[Dmitry Shachnev (mitya57)]

If someone tells me which particular commits I should backport, I will do it.

[Lakshminarayanan Seshadri (lnarayanan-seshadri)]

It appears to do with either the "Tooltip" feature or interaction of gnome-panel(via flashback) with Unity app-menu.
In my 12.04 LTS with gnome fallback the tooltip text appears properly and gnome-panel is very quiet. So the issue must be with tooltip feature simply or some other changes. Anyway i do not know details of bugs /changes in that area.
Since my machine at moment has no space for trying out latest builds(already running 3 flavors) i leave it here . Would update if i get more data.

[Alberts Muktupāvels (muktupavels)]

Do you have same problem in 20.04+?

[Launchpad Janitor (janitor)]

[Expired for gnome-panel (Ubuntu) because there has been no activity for 60 days.]