Re: ssCpuRaw*: wait, kernel, and interrupt 'may be included in system': for Solaris/Linux are they included in ssCpuRawSystem? is there documentation for when they are and when they are not?

On 05/03/2008, Max <[email protected]> wrote:
>  I admittedly haven't checked the code yet, but does anyone on this
>  list know if for Linux the System CPU counter does include the
>  additional wait, interrupt, and kernel metrics or are they counted
>  separately?

That's really a question for the Linux kernel people.
The Linux code for this is effectively:

            read("/proc/stat", buff);
            sscanf(buff, "%llu %llu %llu %llu %llu %llu %llu", &cusell,
                   &cicell, &csysll, &cidell, &ciowll, &cirqll, &csoftll);

        cpu->user_ticks = (unsigned long)cusell;
        cpu->nice_ticks = (unsigned long)cicell;
        cpu->sys_ticks  = (unsigned long)csysll;
        cpu->idle_ticks = (unsigned long)cidell;
            cpu->wait_ticks   = (unsigned long)ciowll;
            cpu->intrpt_ticks = (unsigned long)cirqll;
            cpu->sirq_ticks   = (unsigned long)csoftll;

(with those last three being 0 for 2.4 kernels).
So we're really just reporting the contents of /proc/stat


>            How about Solaris?

The equivalent code here is:

    kstat_read(kstat_fd, ksp, &cs);
            cpu2->user_ticks = (unsigned long)cs.cpu_sysinfo.cpu[CPU_USER];
            cpu2->idle_ticks = (unsigned long)cs.cpu_sysinfo.cpu[CPU_IDLE];
            cpu2->kern_ticks = (unsigned long)cs.cpu_sysinfo.cpu[CPU_KERNEL];
            cpu2->wait_ticks = (unsigned long)cs.cpu_sysinfo.cpu[CPU_WAIT];
              /* or cs.cpu_sysinfo.wait[W_IO]+cs.cpu_sysinfo.wait[W_PIO] */
            cpu2->sys2_ticks = (unsigned long)cpu2->kern_ticks+cpu2->wait_ticks;
                /* nice_ticks, intrpt_ticks, sirq_ticks unused */

Note that system here is kernel + wait.



This inconsistency is partly why I would like to define a new CPU MIB.
That and a desire to support per-CPU statistics, rather than just the
current overall figures.



>  RTFM responses with pointers of where I can start to look in the code
>  for the Solaris and Linux variants of the UCD MIB (if there are any)
>  are welcome as well!

The clearest code is probably that under 'mibgroup/hardware/cpu',
where there's a separate code file for each architecture.   See the
routine 'netsnmp_cpu_arch_load'.
   The contents of these are basically the same as those from the
earlier 'mibgroup/ucd-snmp/vmstat*.c' files.

Dave

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