[12] RFR(S): 8177899: Tests fail due to code cache exhaustion on machines with many cores

[Tobias Hartmann]

Hi Martin,

thanks for looking at this.

On 25.10.18 12:09, Doerr, Martin wrote:
> I only wonder if using C2Compiler::initial_code_buffer_size() makes sense. Should we really start a C2 compiler thread for 5kB of code cache?
> I'd prefer to use some feasible constant.

Well it's just an upper limit and the number of compiler threads that are actually created should be
controlled by -XX:+UseDynamicNumberOfCompilerThreads. I think the heuristic should be improved to
consider the available space in the code cache as well (not only the available memory). Since the
available space in the code cache depends on many factors, I don't think a constant is feasible. I
would prefer to file a RFE for that.

While looking at the computation again, I've noticed that JDK-8209594 increased the buffer size.
I've updated C2Compiler::initial_code_buffer_size() accordingly:
http://cr.openjdk.java.net/~thartmann/8177899/webrev.02/

Best regards,
Tobias