Hello,
couldn't sleep last night, and came to ask myself the following
question, which I now pass to the list. Any feedback is welcome.
Imagine having your linux desktop open, with several (heavy) user
space applications running, locally and over the network.
For example, the Gimp is applying some filter to a large image and
redrawing it, StarCalc is updating totals and graphs inside a big
spreadsheet, some ftp is ongoing, and you are browsing your Imap
folders on the server.
THE QUESTION:
In such a context, how much do a modern kernel and Xfree pair "impact"
on overall performance? In other words, of 1000 CPU clock cycles, how
many would be spent executing actual application code in the CPU, and
how many for all the system functions, or just waiting for interrupts?
By "system" here I refer to *everything* else: process scheduling,
swapping, file system management/journalling, loading instruction into
the CPU, loading data to and from disk, redrawing the screen, keep all
the TCP/IP/PPP/firewalling protocols going, etc..
Of course, without a multitasking kernel with networking included and
a windowing system nothing would happen at all, but I'd really like to
figure out exactly what "price" we pay for it, just out of curiosity.
I have tried to sum all the processes ran by root on my workstation,
and came out with system stuff requiring 0.8% of CPU, 9.6% of RAM. Is
this the right answer to my question, or there is a better way to
calculate this?
Ciao,
Marco
