Re: Introduce a New Metrics to measure Load average.

From: Erik Mouw
Date: Wed Jun 14 2006 - 08:47:03 EST


On Wed, Jun 14, 2006 at 03:12:29PM +1000, sena seneviratne wrote:
> The problem with the load metric of current Linux/Unix is that it measures
> CPU load and Disk load without indicating the true nature of the load,
> thereby creating some confusion among the readers. For example, if a CPU
> bound task switches on to read a large chunk of disk data, then the load
> average value would still continue to indicate this activity as a load, yet
> the true CPU load during this period would have been zero.

Right, we've seen such things with busy servers.

> This situation
> triggered us to make necessary additions to the kernel so that CPU load and
> Disk load could be reported separately. Further the specialisation of load
> helped our model to perform predictions when there is interference between
> CPU and Disk IO loads.

OK.

> In the user mode, a new proc file called /proc/loadavgus would collect the
> new data according to a new format which would look like the following,
>
> CPU Disk
> Root 0.7 0
> User1 0.9 1
> User2 0.9 0
> User3 1.03 1
> User4 0.93 0
> User5 1.0 0

The kernel doesn't know about user names, only uids. So the layout
should be something like:

CPU Disk
0 0.7 0
500 0.9 1
501 0.9 0

> What do you think about this change?

Why do you want to tell the load per user? Just the CPU and disk load
should be sufficient.


Erik

--
+-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands
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