topic Re: vmstat and acceptable value for cs (context switches) in Operating System - Linux

vmstat and acceptable value for cs (context switches)

Louis Coilliot — Tue, 13 May 2008 20:45:28 GMT

Hello,

I wonder what is the range for acceptable values of context switches for up-to date Intel x86 processors (let's say, a Xeon® X5460 Quad Core 3.16 Ghz for example).

I can't find any recent information about this.

The fresher information I found is an article of 2002 that says (in substance):
A lot of context switching = greater than 20 000 per second.

If I apply Moore's Law, that would make 160 000
for a CPU in 2008.

Does anyone has informations on this ?

Let me know, thanks.

Louis Coilliot

Re: vmstat and acceptable value for cs (context switches)

Ivan Ferreira — Tue, 13 May 2008 21:24:58 GMT

The true is that, I never used CS as a performance parameter. I don't think that there is a "suggested" value, it depends of the system, drivers and applications.

Focus on other performance counters.

Re: vmstat and acceptable value for cs (context switches)

Louis Coilliot — Tue, 13 May 2008 21:35:04 GMT

Hmmm, this sounds like a kind of "tell me your need, i'll show you how to do without" answer.

I indeed also use other metrics.

But the values of the run queue AND cswitch/s can tell me if it is better to add more processors or to put a more powerfull processor.

Thanks, anyway.

Louis Coilliot

Re: vmstat and acceptable value for cs (context switches)

Ivan Ferreira — Wed, 14 May 2008 13:34:37 GMT

I agree tha runq is a metric, related with idle CPU and load average. But still I don't know how CS can give you good/bad values.