Messages in this thread | | | Subject | Re: [RFC][PATCH] IO wait accounting | From | Zlatko Calusic <> | Date | Mon, 13 May 2002 13:45:54 +0200 |
| |
Rik van Riel <riel@conectiva.com.br> writes:
> On Sun, 12 May 2002, Zlatko Calusic wrote: >> Rik van Riel <riel@conectiva.com.br> writes: >> > >> > And should we measure read() waits as well as page faults or >> > just page faults ? >> >> Definitely both. > > OK, I'll look at a way to implement these stats so that > every IO wait counts as iowait time ... preferably in a > way that doesn't touch the code in too many places ;) > >> Somewhere on the web was a nice document explaining >> how Solaris measures iowait%, I read it few years ago and it was a >> great stuff (quite nice explanation). >> >> I'll try to find it, as it could be helpful. > > Please, it would be useful to get our info compatible with > theirs so sysadmins can read their statistics the same on > both systems. >
Yes, that would be nice. Anyway, finding the document I mentioned will be much harder than I thought. Googling last 15 minutes didn't make progress. But, I'll keep trying.
Anyway, here is how Aix defines it:
Average percentage of CPU time that the CPUs were idle during which the system had an outstanding disk I/O request. This value may be inflated if the actual number of I/O requesting threads is less than the number of idling processors.
(http://support.bull.de/download/redbooks/Performance/OptimizingYourSystemPerformance.pdf)
Also, Sun has a nice collection of articles at http://www.sun.com/sun-on-net/itworld/, and among them http://www.sun.com/sun-on-net/itworld/UIR981001perf.html which speaks about wait time, but I'm still searching for a more technical document... -- Zlatko - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |