If you are going to fix it, could you add a microstate for iowait so we have an accurate per process measure of blocked on diskio. I think I filed a bug on this about 5 years ago or more... We already have a microstate for page-in wait.
Adrian On 10/18/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Adrian, biowait() still updates cpu_stats.sys.iowait. This means that Solaris is still keeping track of the number of threads that are blocked waiting for I/O. I see no reason not to expose this value to the user. I certainly do not intend to re-introduce a CPU percentage of time waiting for I/O, however. -j On Wed, Oct 18, 2006 at 05:37:15PM -0700, adrian cockcroft wrote: > The algorithm for iowait used to be something like: if idle and vmstat > b nonzero then iowait > So on Solaris 10, vmstat b is gone as well as iowait. If you want to > see how much time you are waiting for io, use iostat and add up the > times for each disk. > > Here is one way it was broken, a cpu starts an io, a different cpu > completes the io, which cpu was waiting? > > Adrian > > On 10/18/06, Mike Gerdts <[EMAIL PROTECTED]> wrote: > >On 10/18/06, adrian cockcroft <[EMAIL PROTECTED]> wrote: > >> In Solaris 10, iowait is no longer measured and will be reported as > >> zero by existing tools. Since iowait was always a variant of idle > >> time, this makes no difference to usr or sys time. > >> iowait was always a confusing and useless metric, which is why it was > >removed. > > > >On a related note, I have yet to see vmstat's "b" (kernel threads > >blocked on I/O) column be non-zero. This includes a large RAC > >environment where the previous measure of I/O health was (don't shoot > >the messenger!) iowait. The same workload on S9 consistently showed > >non-zero values in the "b" column. > > > >Has the meaning of this value changed as well, or is Solaris 10 just > >that much better at getting I/O out of the queue? > > > >TIA, > >Mike > > > >-- > >Mike Gerdts > >http://mgerdts.blogspot.com/ > > > _______________________________________________ > perf-discuss mailing list > perf-discuss@opensolaris.org
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