872780 - Defect - Metro Firefox uses 7-10% of CPU when idle

Status: VERIFIED FIXED

(Firefox for Metro Graveyard :: Browser, defect, P1)

Description

[Brian R. Bondy [:bbondy]]

Asa noticed that Metro Firefox uses some CPU non stop when it is idle, even with a blank profile.  Jim and myself both reproduced this. I was seeing 7-10% of CPU usage!!!

I think Jim did a preliminary investigation using profiling in Visual Studio and found that it is painting code.

Comment 1

[Brian R. Bondy [:bbondy]]

Juan could you get a regression range on this? We think it happened recently.

Comment 2

[Brian R. Bondy [:bbondy]]

Blocking story depends on what the regression window finds.

Comment 3

[Brian R. Bondy [:bbondy]]

p=3

Comment 4

[juan becerra [:juanb]]

In progress.

Comment 5

[juan becerra [:juanb]]

I have been trying to reproduce the problem, but I don't think I see it. I'm using nightly builds you can get from ftp. I went back to 5/02 and worked my way up to tonight's build, but I can't reproduce the 7%-10 CPU usage while idle.

My steps:
1. Open Metro Firefox and leave it at the Start page
2. Check Task Manager entry for Nightly
3. Alt-tab between Metro Firefox and the Task Manager

I've tried this while having the Google page open.

I have not been able to see anything past 5% CPU usage, and if it is the plan Start page in Metro Firefox, I don't see anything past 2%, and it is only temporarily while doing alt-tab. After a few seconds it goes to 0% and the process is listed as suspended.

Any suggestions I can follow to try to reproduce this problem?

Comment 6

[Asa Dotzler [:asa]]

Anything above zero on Firefox start after it's loaded is a bug. Perhaps it's been around for longer than we imagined? I'll see if I can find a build that doesn't put my cpu under load and report back.

Comment 7

[Brian R. Bondy [:bbondy]]

You can try putting Firefox into snapped view so it doesn't suspend.

Comment 8

[Jim Mathies [:jimm]]

This is still a valid bug with omtc enabled.

Comment 9

[Jim Mathies [:jimm]]

This is only reproducing for me on the start page, and is definitely paint related.

Comment 10

[Jim Mathies [:jimm]]

(In reply to Jim Mathies [:jimm] from comment #9)
> This is only reproducing for me on the start page, and is definitely paint
> related.

Not necessarily painting since the widget isn't being invalidated, but the refresh driver is triggering all sorts of callbacks that don't fire on content.

Comment 11

[Jim Mathies [:jimm]]

Attachment: fix

Two problems here - the css throbber we have in the sync flyout and the png throbber we have in the privacy flyout were continuing to animate despite not being visible. I experimented around with various display / visibility settings but ultimately ended up having to ditch the png and "turn off" the css animation to get this fixed.

Comment 12

[Jim Mathies [:jimm]]

Comment on attachment 771883 [details] [diff] [review]
fix

This gives us a nice little performance boost too.

Comment 13

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/0706e520e09c
https://hg.mozilla.org/mozilla-central/rev/2636fd9a8df8

Comment 14

[Samvedana (:Samvedana)]

User Agent : Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:25.0) Gecko/20130717 Firefox/25.0
Build ID: 20130717030207

WFM-Iteration 10
Tested on latest nightly from ftp://ftp.mozilla.org/pub/firefox/nightly/2013/07/2013-07-17-03-02-07-mozilla-central/ 
using windows 8.1 preview and I see 0% CPU usage with Google page opened in nightly.

Comment 15

[Samvedana (:Samvedana)]

User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0
Build ID: 20130816030205
Built from http://hg.mozilla.org/mozilla-central/rev/1ed5a88cd4d0

WFM
Tested on windows 8 using latest nightly for iteration-12. I see 0% CPU usage with Google page opened in nightly