Sorry,
Latests official glibc in system dependent implementation for Linux simply
use MAKE_THREAD_CPUCLOCK
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/pthread_getcpuclockid.c;h=f5af64ea88b92e64ed86c4a9ca254bbceb103b29;hb=9fe3c80c7c3dbce34dadc7f0693d211fdd9a0b03
On Wed, Apr 26, 2017 at 2:22 AM, Sergey Korolev <s.koro...@ndmsystems.com>
wrote:
> Current uClibc-ng version incorrectly calculates clockid
> in pthread_getcpuclockid (at least for modern kernels). The simplest test
> program
>
> #include <time.h>
> #include <errno.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <pthread.h>
>
> int main()
> {
> clockid_t clk;
> struct timespec ts;
> const int err = pthread_getcpuclockid(pthread_self(), &clk);
>
> if (err != 0) {
> errno = err;
> perror("pthread_getcpuclockid");
> return EXIT_FAILURE;
> }
>
> if (clock_gettime(clk, &ts) == -1) {
> perror("clock_gettime");
> return EXIT_FAILURE;
> }
>
> printf("Thread time is %lu.%06lu.\n",
> ts.tv_sec,
> ts.tv_nsec / 1000);
>
> return EXIT_SUCCESS;
> }
>
> fails with
>
> clock_gettime: Invalid argument
>
> Tested on Linux 3.4 / MIPS built with GCC 5.4.0.
>
> Other implementations, for example musl, use a simple calculation
> https://git.musl-libc.org/cgit/musl/tree/src/thread/
> pthread_getcpuclockid.c
>
> Looks strange, but the official glibc repository
> https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=nptl/
> pthread_getcpuclockid.c;hb=HEAD
> has the same implementation as in uClibc-ng.
>
> This fork https://github.com/lattera/glibc/blob/master/
> nptl/sysdeps/unix/sysv/linux/pthread_getcpuclockid.c
> use more accurate approach relying on __NR_clock_getres (defined in the
> kernel since 2.6.24) with MAKE_THREAD_CPUCLOCK macro copied from the kernel
> (http://lxr.free-electrons.com/source/include/linux/
> posix-timers.h?v=2.6.24#L34, Linux 4.10 has the same one).
>
> I propose an intermediate solution: use MAKE_THREAD_CPUCLOCK like
> computation of clockid when __NR_clock_getres defined and do a fallback to
> an older implementation when not.
>
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