[LTP] [PATCH] [syscalls] getrusage04: new testcase

[Caspar Z. <cz...@re...>]

getrusage04 - accuracy of getrusage() with RUSAGE_THREAD

This program is used for testing the following upstream commit:
761b1d26df542fd5eb348837351e4d2f3bc7bffe.

getrusage() returns cpu resource usage with accuracy of 10000us
when RUSAGE_THREAD is specified to the argument who. Meanwhile,
accuracy is 1000us when RUSAGE_SELF is specified. This bad
accuracy of getrusage() caused a big impact on some application
which is critical to accuracy of cpu usage. The upstream fix
removed casts to clock_t in task_u/stime(), to keep granularity
of cputime_t over the calculation.

Signed-off-by: Caspar Zhang <cz...@re...>
---
 runtest/syscalls                                  |   11 +-
 testcases/kernel/syscalls/getrusage/getrusage04.c |  122 +++++++++++++++++++++
 2 files changed, 128 insertions(+), 5 deletions(-)
 create mode 100644 testcases/kernel/syscalls/getrusage/getrusage04.c