[wplug] Understanding Load

[Martin James Gehrke]

Load is a very deceptive number. It is not uncommon for a file server to
have a load equal to the number of nfsd threads.

Gary P is also right that load can be heavily influenced by your processes
in disk wait.

The numerical number of load is used to communicate the CPU queue length,
the number of processes queued up for CPU time.

Marty

System and Network Administrators of Pittsburgh <http://snapgh.com>

On Wed, Dec 7, 2011 at 1:37 PM, Gary P <gpitman at gmail.com> wrote:

> My understanding of load is that your machine can process a load of 1/per
> core. If you have an 8 core machine and a load of 8 then your machine is
> getting as much work as it can handle.
> Since load is not consistant you should target a consistant load of .7 per
> core so that spikes can be recovered from.
> However I/O wait can drive your load through the roof without working your
> server at all.
>
> - Gary
>
> On Dec 7, 2011, at 12:59 PM, Kevin Squire <gentgeen at wikiak.org> wrote:
>
> > I have been diving into the performance of one of our servers lately.
> > Trying to figure out if the hit in performance is due to one of the
> > changes made at network level, server level, or is it just that the
> > server is getting used more.
> >
> > On thing I am trying to understand is "Load" ... the systems (1min) load
> > during the day can go as high as 80 ... but tends to bounce around 3-10
> >
> > We have a Intel® Xeon® Processor 3050
> >
> http://ark.intel.com/products/27204/Intel-Xeon-Processor-3050-%282M-Cache-2_13-GHz-1066-MHz-FSB%29
> >
> > It is Dual Core -- and from what I read here
> >
> http://blog.scoutapp.com/articles/2009/07/31/understanding-load-averages
> >
> > A load of < 2 is OK since it is a dual core.  What I am wondering:
> >
> > 1) Is that right, < 2 is OK for this chip?
> > 2) Does the number of threads matter any?
> > 3) If 2 is right... then where else can I look to see WHY my load tends
> > to spend sooo much time in the double digits?
> >
> >
> >
> > --
> > http://www.wikiak.org
> >
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