1371659 - Google Search profile

Status: REOPENED

(Core :: JavaScript Engine, defect, P3)

Description

[Filip Andrei]

1.Start browser
2.Access google.ro
3.Start Gecko profile
4.Search for 'fox'
5.Share profile


Gecko profile:
 https://perfht.ml/2r1SIOH

Comment 1

[Bobby Chien]

Hi miko, could you help to have the first investigation? thanks.

Comment 2

[Miko Mynttinen]

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.

Comment 3

[Filip Andrei]

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:
https://perf-html.io/public/5f91b21d37ee7d6e6fd2c726721b275c3e7e7630/calltree/?hiddenThreads=&thread=3&threadOrder=0-2-3-4-5-1-6

Comment 4

[Miko Mynttinen]

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?

Comment 5

[Filip Andrei]

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

Comment 6

[Jean Gong :jgong]

sorry, I changed the status by mistake.

Comment 7

[Markus Stange [:mstange]]

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.

https://perfht.ml/2eP9Tl2

I've also enabled stylo because I saw a bunch of sync restyles in the profile.

Comment 8

[Bobby Chien]

Missing [qf] flag

Comment 9

[(no longer active)]

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.

Comment 10

[Bobby Chien]

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.

Comment 11

[Filip Andrei]

Hi Bobby,


Here is the profile requested https://perfht.ml/2g5bKmy

Comment 12

[Bobby Chien]

Markus, could you help to analyze the profile again? Thanks. Comment 11.

Comment 13

[Markus Stange [: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.

Comment 14

[Bobby Chien]

Tracking under Quantum Flow.