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Allocator Comparison

Contacts:
Chris Waterson (waterson@netscape.com)

gtkEmbed

Gross Virtual Memory Usage

Below is a graph that compares the gross virtual memory utilization of some common memory allocators. The data was collected from the /proc filesystem while a full1 gtkEmbed build from 2001-01-04 ran through approximately 550 “top” URLs. (Due to crash bugs in gtkEmbed, some of the runs have been truncated.)

Allocator Comparison, gtkEmbed

The graph is showing the total amount of virtual memory required for the malloc() heap. This number was calculated by subtracting the process’s stack, static data, and code size (approximately 18MB) from the process’s total VM size.

The Ideal line was computed by analyzing a log of allocations performed during one of the runs, and maintaining a running counter of how much heap data was “live” at any one time. As such, it charts the amount of VM that a “perfect” allocator (one without block overhead or fragmentation) would use.

Resident Set Usage

TBD

Performance

The below graph shows the mean load times for a 2001-01-17 optimized gtkEmbed build using the stock glibc allocator, the lea-2.7.0pre6 allocator, and the lea-2.7.0pre7 allocator. Data was collected by loading the URLs in sequence ten times; i.e., www.sun.com, then news.cnet.com, ..., then home.netscape.com, then www.sun.com, and so forth. The content for each site was downloaded from the Internet and stored on a web server accessable via local-area network to minimize network interference. On average, gtkEmbed with the lea-2.7.0pre6 allocator was about 5% slower than with the glibc allocator, and about 8% slower with the lea-2.7.0pre7 allocator. 2

Allocator Performance Comparison

winEmbed

Gross Virtual Memory Usage

TBD

Resident Set Usage

TBD

1 By “full”, I mean that gtkEmbed was run from the “stock” mozilla directory. It therefore tends to load more componentry that a “minimal” embed build.

2 The raw data is avaialable here as a tab-delimited text file.