Open Bug 1371659 Opened 7 years ago Updated 2 years ago

Google Search profile


(Core :: JavaScript Engine, defect, P3)

55 Branch
Windows 10



Performance Impact low


(Reporter: afilip, Unassigned)


(Blocks 1 open bug, )


(Keywords: perf, Whiteboard: [QRC][QRC_Analyzed])

1.Start browser
3.Start Gecko profile
4.Search for 'fox'
5.Share profile

Gecko profile:
Assignee: nobody → gandalf
Assignee: gandalf → nobody
Hi miko, could you help to have the first investigation? thanks.
Assignee: nobody → mikokm
Flags: needinfo?(mikokm)
Are there performance problems with the site?

The profile is 12 seconds long, and the most time spent in one function is just 14ms (0.2% total). The lack of data in the profile hints that the profiler sampling interval is higher than what most function calls take. As such this profile is not actionable.
Flags: needinfo?(mikokm) → needinfo?(afilip)
There is a delay in google search and I changed the profiler interval to 0.07 ms and increased Buffer to 540mb

Here is the profile and hope that helps:
Flags: needinfo?(afilip)
Thank you for the refined profile. Unfortunately, aside from one lengthy call to nsDisplayList::GetClippedBoundsWithRespectToASR(), I can't really see anything that would imply a problem.

Most of the time in the profile seems to be spent waiting for events. This could be, for example, because of a slow network connection. Is anything done to rule out this as the source of slowdown?
Flags: needinfo?(afilip)
Assignee: mikokm → nobody
The problem here is the Quantum reference hardware because is not very fast and when I start Gecko profiler it freeze for a couple of seconds and related to the network i just did a speed-test and the results are 49.95 Download and 53.03 Upload
Flags: needinfo?(afilip)
Depends on: 1382701
Closed: 7 years ago
Resolution: --- → FIXED
Whiteboard: [QRC][QRC_NeedAnalysis] → [QRC][QRC_Analyzed]
sorry, I changed the status by mistake.
Resolution: FIXED → ---
Here's a profile of the steps in comment 0 with dom.ipc.processCount.web set to 1 and the profiling interval set to 3ms.
These settings seem to produce profiles that don't have strange gaps in them.

I've also enabled stylo because I saw a bunch of sync restyles in the profile.
Missing [qf] flag
Whiteboard: [QRC][QRC_Analyzed] → [qf][QRC][QRC_Analyzed]
Removing the [qf] flag because this bug isn't actionable as nobody seems to have came up with an analysis of what shows up in the profile.  Sorry but we keep running into bugs without any analysis in the triage meeting and we can't spend time to analyze profiles during triage.
Whiteboard: [qf][QRC][QRC_Analyzed] → [QRC][QRC_Analyzed]
Go back for analysis. 

Hi Filip,

Since the profile is a month old, could you help to create new profile data? Then I will assign the bug for analysis. Thanks.
Flags: needinfo?(afilip)
Whiteboard: [QRC][QRC_Analyzed] → [QRC][QRC_NeedAnalysis]
Hi Bobby,

Here is the profile requested
Flags: needinfo?(afilip)
Markus, could you help to analyze the profile again? Thanks. Comment 11.
Flags: needinfo?(mstange)
Here's what I found:
 - Most of the jank is due to JS execution.
 - There are multiple synchronous reflows and restyles within that JS execution, but they don't take up much time.
 - The first two reflows and the first restyle are quite slow because they get font information from the system. This only happens the first time these fonts are encountered in a given content process.
 - There are multiple paints that take slightly longer than 16ms.
Flags: needinfo?(mstange)
Tracking under Quantum Flow.
Component: General → JavaScript Engine
Whiteboard: [QRC][QRC_NeedAnalysis] → [qf][QRC][QRC_Analyzed]
Whiteboard: [qf][QRC][QRC_Analyzed] → [qf:p2][QRC][QRC_Analyzed]
Keywords: perf
Priority: -- → P3
Whiteboard: [qf:p2][QRC][QRC_Analyzed] → [qf:p3][QRC][QRC_Analyzed]
Performance Impact: --- → P3
Whiteboard: [qf:p3][QRC][QRC_Analyzed] → [QRC][QRC_Analyzed]
Severity: normal → S3
You need to log in before you can comment on or make changes to this bug.