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The hardware sampler creates samples that are processed at a later point in time. The PID and TID values of the perf samples that are created for hardware samples are initialized with values from the current task. Hence, the PID and TID values are not correct and perf samples are associated with wrong processes. The PID and TID values are obtained from the Host Program Parameter (HPP) field in the basic-sampling data entries. These PIDs are valid in the init PID namespace. Ensure that the PIDs in the perf samples are resolved considering the PID namespace in which the perf event was created. To correct the PID and TID values in the created perf samples, a special overflow handler is installed. It replaces the default overflow handler and does not become effective if any other overflow handler is used. With the special overflow handler most of the perf samples are associated with the right processes. For processes, that are no longer exist, the association might still be wrong. Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.