Hi Erik , is there some info available about the performance impact when disabling disabling speculative execution ?
And which compiler versions are needed for this ? Best regards, Matthias >We need to add compilation flags for disabling speculative execution to >our native libraries and executables. In order to allow for users not >affected by problems with speculative execution to run a JVM at full >speed, we need to be able to ship two JVM libraries - one that is >compiled with speculative execution enabled, and one that is compiled >without. Note that this applies to the build time C++ flags, not the >compiler in the JVM itself. Luckily adding these flags to the rest of >the native libraries did not have a significant performance impact so >there is no need for making it optional there. > >This patch defines flags for disabling speculative execution for GCC and >Visual Studio and applies them to all binaries except libjvm when >available in the compiler. It defines a new jvm feature >no-speculative-cti, which is used to control whether to use the flags >for libjvm. It also defines a new jvm variant "altserver" which is the >same as server, but with this new feature added. > >For Oracle builds, we are changing the default for linux-x64 and >windows-x64 to build both server and altserver, giving the choice to the >user which JVM they want to use. If others would prefer this default, we >could make it default in configure as well. > >The change in GensrcJFR.gmk fixes a newly introduced race that appears >when building multiple jvm variants. > >Bug: https://bugs.openjdk.java.net/browse/JDK-8202384 > >Webrev: http://cr.openjdk.java.net/~erikj/8202384/webrev.01
