llvm-project.git/libc/src/time/gpu/clock_gettime.cpp, branch users/nico/python-2 Unnamed repository; edit this file 'description' to name the repository. Reapply "[libc][windows] start time API implementation (#117775)" (#118886) 2024-12-05T23:21:03+00:00 Schrodinger ZHU Yifan yifanzhu@rochester.edu 2024-12-05T23:21:03+00:00 e6cf5d2863b77895ae7183952514bedd9e8dde16 






[libc] Implement `clock_gettime` for the monotonic clock on the GPU (#99067)
2024-07-16T21:17:34+00:00

Joseph Huber
huberjn@outlook.com

2024-07-16T21:17:34+00:00

8393ea5d1dd8e8b56a87a6edbca31fb8722cee48

Summary:
This patch implements `clock_gettime` using the monotonic clock. This
allows users to get time elapsed at nanosecond resolution. This is
primarily to facilitate compiling the `chrono` library from `libc++`.
For this reason we provide both `CLOCK_MONOTONIC`, which we can
implement
with the GPU's global fixed-frequency clock, and `CLOCK_REALTIME` which
we cannot. The latter is provided just to make people who use this
header happy and it will always return failure.




Summary:
This patch implements `clock_gettime` using the monotonic clock. This
allows users to get time elapsed at nanosecond resolution. This is
primarily to facilitate compiling the `chrono` library from `libc++`.
For this reason we provide both `CLOCK_MONOTONIC`, which we can
implement
with the GPU's global fixed-frequency clock, and `CLOCK_REALTIME` which
we cannot. The latter is provided just to make people who use this
header happy and it will always return failure.