Travis Crawford stated:
< Thanks Menno and Jim! I'm looking around the Apple documentation to
< hopefully find where they store the load average. Yes, it would be
< nice to have all the source available; I should take a better look at
< opensolaris.
Why not browse the Apple port of The DTraceToolkit itself ?
It uses averunnable.ldavg instead of the Solaris specific hp_avenrun.
Found from having a look at the OS-X port of DTrace at:
http://www.opensource.apple.com/darwinsource
Regards,
Sean.
.
<
< --travis
<
<
< On Mon, Mar 31, 2008 at 12:02 AM, Jim Mauro <[EMAIL PROTECTED]> wrote:
< > Hi Travis - Your first clue here is the backtick operator (`) used to
< > extract hp_avenrun[0]. The backtick operator is used to read the
< > value of kernel variables, which will be specific to the running kernel.
< > That is, Solaris, Mac OS X (Darwin), FreeBSD and all other kernels
< > with DTrace will not have portability when it comes to dtrace scripts
< > that use the backtick variable, since by definition they will be kernel
< > specific.
< >
< > hp_avenrun[] is a Solaris kernel variable:
< >
< >
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/os/clock.c#97
< >
< > For some kernel variables (like avenrun), you could look around for
< > something
< > similar in your target kernel:
< >
< > kilroy> nm -x /mach_kernel | grep avenrun
< > 004d25ac 0f 08 0000 0002dbb9 _avenrun
< > kilroy>
< >
< > Of course, without the source, it's not clear what the variable type is....
< >
< > So....your example below is specific to Solaris. If you see the backtick
< > operator, think "kernel specific".
< >
< > HTH,
< > /jim
< >
< >
< >
< > Travis Crawford wrote:
< > > Hi dtrace-discuss,
< > >
< > > Having recently upgraded to OS X 10.5 I'm relatively new to DTrace, so
< > > apologies if this has been covered before; I did search the archives
< > > and didn't find anything though.
< > >
< > > As a DTrace starter project I'd like to understand how to extract
< > > common performance metrics before diving too far in. One of these
< > > common metrics is load average, which I thought would be pretty easy.
< > > However, I'm confused by this code snippet (from
< > > http://www.brendangregg.com/DTrace/iotop):
< > >
< > > """
< > > /* fetch 1 min load average */
< > > this->load1a = `hp_avenrun[0] / 65536;
< > > this->load1b = ((`hp_avenrun[0] % 65536) * 100) / 65536;
< > > """
< > >
< > > I can't figure out where hp_avenrun is defined. I searched
< > > http://wikis.sun.com/display/DTrace as well as looking at all the
< > > probes on my system ($ sudo dtrace -l | grep hp_avenrun) and came up
< > > empty.
< > >
< > > So my question is, when reading d scripts, how should I go about
< > > finding out what these mysterious variables are?
< > >
< > > Thanks,
< > > Travis
< > > _______________________________________________
< > > dtrace-discuss mailing list
< > > [email protected]
< > >
< >
< _______________________________________________
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--
Sean.
.
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