Pointer compression in Oilpan · V8

Pointer compression in Oilpan allows for compressing C++ pointers and reducing the heap size by up to 33%.

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Hasnain says:

This continues to increase my motivation to learn more about garbage collectors.

“The numbers reported represent the 50th and 99th percentile for Blink memory allocated with Oilpan across the fleet[2]. The reported data shows the delta between Chrome 105 and 106 stable versions. The absolute numbers in MB give an indication on the lower bound that users can expect to see. The real improvements are generally a bit higher due to indirect effects on Chrome’s overall memory consumption. The larger relative improvement suggests that packing of data is better in such cases which is an indicator that more memory is used in collections (e.g. vectors) that have good packing. The improved padding of structures landed in Chrome 108 and showed another 4% improvement on Blink memory on average.

Because Oilpan is ubiquitous in Blink, the performance cost can be estimated on Speedometer2. The initial prototype based on a thread-local version showed a regression of 15%. With all the aforementioned optimizations we did not observe a notable regression.”

Posted on 2022-11-29T16:53:26+0000