3.54% tp5o_scroll (linux64) regression on push 266e1a6642b1 (Wed Feb 17 2016)




3 years ago
2 years ago


(Reporter: wlach, Assigned: mchang)


({perf, regression})

perf, regression
Dependency tree / graph

Firefox Tracking Flags

(Not tracked)


(Whiteboard: [talos_regression])

Mason, could you take a look at this? I did some retriggers in the area and it looks like your patch is the culprit.

From what data I've gathered so far, this appears to only happen on linux64 non-e10s, so I guess you might question how important this is...



Talos has detected a Firefox performance regression from push 266e1a6642b1. As author of one of the patches included in that push, we need your help to address this regression.

This is a list of all known regressions and improvements related to the push:


On the page above you can see an alert for each affected platform as well as a link to a graph showing the history of scores for this test. There is also a link to a treeherder page showing the Talos jobs in a pushlog format.

To learn more about the regressing test(s), please see:


Reproducing and debugging the regression:

If you would like to re-run this Talos test on a potential fix, use try with the following syntax:

try: -b o -p linux64 -u none -t g1 --rebuild 5  # add "mozharness: --spsProfile" to generate profile data

(we suggest --rebuild 5 to be more confident in the results)

To run the test locally and do a more in-depth investigation, first set up a local Talos environment:


Then run the following command from the directory where you set up Talos:

talos --develop -e <path>/firefox -a tp5o_scroll

(add --e10s to run tests in e10s mode)

Making a decision:

As the patch author we need your feedback to help us handle this regression.
*** Please let us know your plans by Monday, or the offending patch(es) will be backed out! ***

Our wiki page outlines the common responses and expectations:

Flags: needinfo?(mchang)
Component: Untriaged → Graphics
Product: Firefox → Core


3 years ago
Assignee: nobody → mchang
Flags: needinfo?(mchang)

Comment 1

3 years ago
Did some perfherder runs:


The regression comes from memsetting allocated memory here - http://mxr.mozilla.org/mozilla-central/source/﷒0﷓

I'm not sure what we can do here. The memsetting has to happen because nsShmImage allocates some memory and directly allocates a draw target with the data instead of going the route of TextureClient::CreateTextureForDrawing. We need to memset the memory here for correctness when Skia content lands for Linux. I think we have to accept this regression. 

Is that ok?
Flags: needinfo?(jmaher)
Mason, thanks for digging into this and finding the cause.  lets accept this and move forward!
Last Resolved: 3 years ago
Flags: needinfo?(jmaher)
Resolution: --- → WONTFIX
Version: unspecified → Trunk
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