Hi Rodrigo, On Tue, Sep 3, 2013 at 12:05 PM, Rodrigo Campos <rodrigo@xxxxxxxxxxx> wrote: > As confirmed by peterz on IRC, this note is obsolete: > > <peterz> rata: that section is obsolete; CLOCK_THREAD_CPUTIME_ID is good > <peterz> rata: CLOCK_PROCESS_CPUTIME_ID is also correct > > So this patch just removes it. Clearly, the page needs amending. However, ideal would be to describe *when* the section became obsolete (which kernel version). Do you or Peter know, or have an idea how we can determine that information? Cheers, Michael > --- > man2/clock_getres.2 | 32 -------------------------------- > 1 file changed, 32 deletions(-) > > diff --git a/man2/clock_getres.2 b/man2/clock_getres.2 > index 10ecd18..eac97cd 100644 > --- a/man2/clock_getres.2 > +++ b/man2/clock_getres.2 > @@ -218,38 +218,6 @@ indicate that > are available. > (See also > .BR sysconf (3).) > -.SH NOTES > -.SS Note for SMP systems > -The > -.B CLOCK_PROCESS_CPUTIME_ID > -and > -.B CLOCK_THREAD_CPUTIME_ID > -clocks are realized on many platforms using timers from the CPUs > -(TSC on i386, AR.ITC on Itanium). > -These registers may differ between CPUs and as a consequence > -these clocks may return > -.B bogus results > -if a process is migrated to another CPU. > -.PP > -If the CPUs in an SMP system have different clock sources then > -there is no way to maintain a correlation between the timer registers since > -each CPU will run at a slightly different frequency. > -If that is the case then > -.I clock_getcpuclockid(0) > -will return > -.B ENOENT > -to signify this condition. > -The two clocks will then be useful only if it > -can be ensured that a process stays on a certain CPU. > -.PP > -The processors in an SMP system do not start all at exactly the same > -time and therefore the timer registers are typically running at an offset. > -Some architectures include code that attempts to limit these offsets on bootup. > -However, the code cannot guarantee to accurately tune the offsets. > -Glibc contains no provisions to deal with these offsets (unlike the Linux > -Kernel). > -Typically these offsets are small and therefore the effects may be > -negligible in most cases. > .SH BUGS > According to POSIX.1-2001, a process with "appropriate privileges" may set the > .B CLOCK_PROCESS_CPUTIME_ID > -- > 1.7.10.4 > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
