第 9 章 编译程序及工具

GNU 编译器集合（GCC）支持为 System z 二进制文件提供多线程代码补丁。使用 "function attribute" 可为热补选择具体功能，使用 -mhotpatch 命令行选项启用所有功能的热补。

启用热补对软件大小和性能有负面影响。因此建议为具体功能使用热补，而不是为所有功能都提供热补服务。

System z 二进制文件中的 Linux 热补支持在 Red Hat Enterprise Linux 7.0 为技术预览。在 Red Hat Enterprise Linux 7.1 发行本中现在提供全面支持。

Red Hat Enterprise Linux 7 包括 Performance Application Programming Interface（PAPI）。PAPI 是现代微处理器中硬件性能计数器的跨平台接口规格。这些计数器是一小组暂存器，可计算与具体处理器功能关联信号同时出现的时间。监控这些事件可在不同方面帮助分析和调整应用程序性能。

In Red Hat Enterprise Linux 7.1, PAPI and the related libpfm libraries have been enhanced to provide support for IBM POWER8, Applied Micro X-Gene, ARM Cortex A57, and ARM Cortex A53 processors. In addition, the events sets have been updated for Intel Xeon, Intel Xeon v2, and Intel Xeon v3 procesors.

OProfile is a system-wide profiler for Linux systems. The profiling runs transparently in the background and profile data can be collected at any time. In Red Hat Enterprise Linux 7.1, OProfile has been enhanced to provide support for the following processor families: Intel Atom Processor C2XXX, 5th Generation Intel Core Processors, IBM POWER8, AppliedMicro X-Gene, and ARM Cortex A57.

Red Hat Enterprise Linux 7.1 features the java-1.8.0-openjdk packages, which contain the latest version of the Open Java Development Kit, OpenJDK8, that is now fully supported. These packages provide a fully compliant implementation of Java SE 8 and may be used in parallel with the existing java-1.7.0-openjdk packages, which remain available in Red Hat Enterprise Linux 7.1.

Java 8 brings numerous new improvements, such as Lambda expressions, default methods, a new Stream API for collections, JDBC 4.2, hardware AES support, and much more. In addition to these, OpenJDK8 contains numerous other performance updates and bug fixes.

从 powerpc-utils 软件包中删除已弃用的 snap 工具，将其归纳整合到 sosreport 工具中。

Red Hat Enterprise Linux 7.1 在 GNU Debugger（GDB）中支持 64-位 PowerPC little-endian 架构。

Tuna is a tool that can be used to adjust scheduler tunables, such as scheduler policy, RT priority, and CPU affinity. In Red Hat Enterprise Linux 7.1, the Tuna GUI has been enhanced to request root authorization when launched, so that the user does not have to run the desktop as root to invoke the Tuna GUI. For further information on Tuna, see the Tuna User Guide.

With Red Hat Enterprise Linux 7.1, the crash packages are no longer a dependency of the abrt packages. Therefore, crash has been removed from the default installation of Red Hat Enterprise Linux  7 in order to keep the installation minimal. Now, users have to select the Debugging Tools option in the Anaconda installer GUI for the crash packages to be installed.

As a Technology Preview, the network-querying capabilities of the ethtool utility have been enhanced for Red Hat Enterprise Linux 7.1 on IBM System z. As a result, when using hardware compatible with the improved querying, ethtool now provides improved monitoring options, and displays network card settings and values more accurately.

Intel has issued erratum HSW136 concerning Transactional Synchronization Extensions (TSX) instructions. Under certain circumstances, software using the Intel TSX instructions may result in unpredictable behavior. TSX instructions may be executed by applications built with the Red Hat Enterprise Linux 7.1 GCC under certain conditions. These include the use of GCC's experimental Transactional Memory support (-fgnu-tm) when executed on hardware with TSX instructions enabled. Users of Red Hat Enterprise Linux 7.1 are advised to exercise further caution when experimenting with Transaction Memory at this time, or to disable TSX instructions by applying an appropriate hardware or firmware update.