Messages in this thread | | | From | Con Kolivas <> | Subject | Re: [RFC] blkstat | Date | Mon, 13 Jun 2005 20:05:38 +1000 |
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On Mon, 13 Jun 2005 20:02, Nick Piggin wrote: > Con Kolivas wrote: > > On Mon, 13 Jun 2005 19:46, Nick Piggin wrote: > >>Oh, and before I go further, does anyone know of any program > >>or statistic that allows the same functionality? Any comments? > > > > Would something like iostat give similar results? > > The problem with that is that it does not give you a % idle > figure on the block device, so you basically can't see if > the device is becoming a bottleneck.
I've often wondered how iostat gives a %busy figure and whether this translated accurately without further info from the kernel.
> You can kind of guess if you take into account the seeks, > and the throughput, but you're still missing things like > head position (eg. changes throughput), settle time and > rotational latency, and lots of other stuff. > > Thanks, > Nick > > Also, BTW. the way I have done the kernel patch make a > device show 100% utilisation even if it is not doing anything > but waiting for a plug, or an anticipatory scheduler. This > is basically all the end user wants to know, although for > development purposes it may be interesting to know the other > metric too.
That sounds quite useful.
Cheers, Con [unhandled content-type:application/pgp-signature] | |