409175 - Bad js performance regression

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Laurențiu Nicola]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b2) Gecko/2007121120 Firefox/3.0b2
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b2) Gecko/2007121120 Firefox/3.0b2

I know the usual story with "microbenchmarks are useless" and "this benchmark is badly written", but a regression is still a regression and we're talking about a >330% increase in time.


Firefox 3.0 beta 2
Array object 		2636
Date object 		34
Error handling 		228
Math object 		136
RegEx object 		551
String object 		180
DOM 			357
Ajax declarations 	971
Total Duration 		5093

Firefox 2.0.0.7
Array object 		170
Date object 		20
Error handling 		90
Math object 		150
RegEx object 		301
String object 		70
DOM 			260
Ajax declarations 	451
Total Duration 		1512

Reproducible: Always




I don't have any add-ons installed.

Comment 1

[Bob Clary [:bc] (inactive)]

The array speed may be a dupe of bug 403977 ? I don't see the same magnitude of slowness on today's Minefield. The other issues may already be covered by other bugs.

Can you download a nightly Minefield build from <http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-trunk/> and check if you still see the same magnitude of problem?

Comment 2

[Laurențiu Nicola]

Using the nightly build:

Array object 		91
Date object 		33
Error handling 		210
Math object 		135
RegEx object 		408
String object 		161
DOM	 		532
Ajax declarations 	933
Total Duration 		2503

, but the results vary rather wildly, this time (from 2100 ms total time to 3000 ms). The median is 2500.

Comment 3

[Robert Sayre]

I don't see this on Mac. I'll have to try on Windows.

                   Fx2 Mac       Fx3 Nightly Mac
Array object       145           30
Date object        57            22
Error handling     60            93
Math object        91            71
RegEx object       228           162
String object      58            53
DOM                100           78
Ajax declarations  333           349

Total Duration     1072          858

Comment 4

[Laurențiu Nicola]

It figured out that I was comparing apples to oranges: I was not running an official build. With Firefox 2.0.0.11 I get

Array object 		481
Date object 		230
Error handling 		110
Math object 		190
RegEx object 		451
String object 		290
DOM 			581
Ajax declarations 	871
Total Duration 		3204

so Firefox 3 is faster.

Comment 5

[Ryan VanderMeulen [:RyanVM]]

Marking WFM based on comment #4