On Thu, 7 Jan 2021 21:29:32 GMT, Igor Veresov <ivere...@openjdk.org> wrote:
>> test/hotspot/jtreg/vmTestbase/nsk/jvmti/scenarios/hotswap/HS203/hs203t004/hs203t004.java >> line 35: >> >>> 33: * While running the thread, it calls a method (doTask2() ) for >>> number of times (10000). >>> 34: * That would cause this method to be compiled, which causes a >>> jvmti callback for compiled method load. >>> 35: * (Hint : to force method compilation -XX:CompileThreshold=900 is >>> used). >> >> The test still uses (and the comments state it uses) >> -XX:CompileThreshold=900 to force compilation, yet it looks like you needed >> to bump the number of times the method is called from 1000 to 10000 to keep >> this test working. Why doesn't 1000 still work? > > Tiered policy (which the -TieredCompilation emulation mode piggybacks on now) > functions by doing periodic callbacks into the runtime to make policy > decisions. The callback intervals are a power-of-2. So, because of the > resulting rounding I cannot guarantee that the compilation will be triggered > exactly at the specified threshold. Plus there are various adaptive > mechanisms that I kept on even in the emulation mode that may also result in > a method being compiled later than expected. To summarize, in the new world, > the advisable way of triggering a compilation is to use the WB API. If that's > too much effort, make sure that the method that you'd like to compile is > invoked more than 2^(log2(CompileThreshold) + 1) times, plus a bit more. Very > few tests actually depend on the legacy behavior, this just happens to be one > of those. Ok. ------------- PR: https://git.openjdk.java.net/jdk/pull/1985
