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453380318e
Commit a029a4eab3 ("s390/cpumf: Allow concurrent access for CPU Measurement Counter Facility")
added CPU Measurement counter facility access to multiple consumers.
It allows concurrent access to the CPU Measurement counter facility
via several perf_event_open() system call invocations and via ioctl()
system call of device /dev/hwc. However the access via device /dev/hwc
was exclusive, only one process was able to open this device.
The patch removes this restriction. Now multiple invocations of lshwc
can execute in parallel. They can access different CPUs and counter
sets or CPUs and counter set can overlap.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.