Background compilation in a separate thread actually works pretty well. IE9 has been shipping it with Chakra for a while, and Firefox is now getting it (and it improved the benchmarks a lot, especially on ARM).
Good to hear it's gotten better. Admittedly, I wasn't thinking about browser based JITs when I said that :)
I'm actually curious if you have any stats on how much of the time this is being done on actual busy machines where it's going to compete for L1/etc resources vs how often it's able to be offloaded onto an otherwise empty core.
IE i expect their to be a significant difference in the use cases for JIT's like PyPy, which are probably going to sit on shared servers that folks are trying to maximize utilization of, vs desktops where I imagine most browsing probably doesn't use all cores at 100%.
No, AFAIK.
"Tiered compilation, introduced in Java SE 7, brings client startup speeds to the server VM.
...
Tiered compilation is now the default mode for the server VM. "
Again, AFAIK, the server VM still has a significantly different set of tuning than the client VM. In particular, it runs some significantly more complex opts that the client VM does not.
