Thomas Maier-Komor schrieb:
I also iterate only once and search for the modules/classes of interest.
Why do you use strncmp? Are ks_module and Co not guaranteed to be null
terminated or did you mix it up with ks_name which includes the trailing id?
Maybe just a leftover from an earlier implementation which iterated over
ksp->ks_name. strcmp() should be sufficient - the strings are null terminated.
Interesting experience - thanks for sharing it. I'd like to know if the
behavior concerning system_misc has improved with later Solaris releases...
Well, in Solaris 2.6 it took 2-3 seconds to read system_misc on a machine
with 32GB RAM and ~600 MHz CPUs. I skipped Solaris 7 and in 8 the problem
went away - so I don't know if it has been fixed in 7 or 8. The statistics
in system_misc were sometimes even unusable (pp_kernel had ridicilous high
values). Therefor I added some comments in the source code:
/*
* Zugriff auf system_pages braucht extrem viel Zeit (>1s bei 32 GB RAM).
* Gibt es nicht etwas besseres?
*/
if((ksp = kstat_lookup(kc, "unix", -1, "system_pages")) == NULL)
return;
if(!kstat_read(kc, ksp, NULL))
return;
pp->kmem = data_lookup(kc, ksp, "pp_kernel") * pagesize;
/* Bug in älteren Solaris-Versionen */
if(pp->kmem > totalmem)
pp->kmem = 0;
Some other things you should consider (I fell into these traps while writing
my little program):
. altough the network drivers do have 64 bit counters in addition to
the 32 bit ones (obytes64, opackets64, rbytes64, ipackets64) - at
least for the bge driver these counters are still 32 bit values, so
they wrap at 2^32. So don't rely on these values really 64 bits wide.
. If you do DR operations or add/remove disks you have to kstat_close()
kstat_open() again - otherwise you won't notice the changed configuration.
. Also DR: Remember that on large machines if you detach a system board
some cpu_stat%d entries might vanish.
. If you count disk usage remember that SDS/SVM also registers its
devices to kstat. In my program I did calculate a disk I/O summary over
all disks and I wondered why on some machines these values were doubled
or 2.5x:
They were setup with SDS while other machines had VxVM (no kstat)
installed.
. Same goes for disk/partition kstat classes: don't count disk I/O twice.
Basically the relevant portion looks like:
for(ksp = kc->kc_chain; ksp != NULL; ksp = ksp->ks_next)
{
if(ksp->ks_type != KSTAT_TYPE_IO)
continue;
if(!strcmp(ksp->ks_module, "md"))
continue;
if(!strcmp(ksp->ks_class, "partition"))
continue;
kstat_read(kc, ksp, &kio);
pp->rops += kio.reads;
pp->wops += kio.writes;
pp->rbytes += kio.nread;
pp->wbytes += kio.nwritten;
}
Daniel
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