Messages in this thread | | | Date | Tue, 5 Oct 2004 10:29:20 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [PATCH] CPU time clock support in clock_* syscalls |
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I just reviewed the code and to my surprise the simple things like
clock_gettime(CLOCK_PROCESS_CPUTIME_ID) and clock_gettime(CLOCK_THREAD_CPUTIME_ID) are not supported. I guess glibc would have to do multiple calls to add up all the threads in order to get these values. This also leaves glibc in control of clocks and does not allow the kernel to define its own clocks.
The code is pretty invasive and I am not sure that this brings us much nor that it is done the right way.
The kernel interface is rather strange with the bits that may be set for each special clock which is then combined with the pid. It may be advisable to have a separate function call to do this like
get_process_clock(pid,type,×pec)
instead of using the posix calls. The thread specific time measurements have nothing to do with the posix standard and may best be kept separate.
The benefit of the patches that I proposed is that it is a clean implementation of the posix interface, the kernel has full control over posix clocks and that driver specific clocks as well as other time sources can be defined that may also utilize the timed interrupt features of those clock chips. Rolands patch does not allow that and instead will lead to more complex logic in glibc and a rather strange kernel interface. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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