Hey, Some "unaccounted" CPU cycles are consumed for handling software and hardware interrupts and some for managing internal kernel structures like network stack to push packets around or other kernel responsibilities like scheduling or filesystem.
The point is that kernel part of CPU pie could not be always mapped to a specific process, that's why benchmarks for IO intensive software systems generally speak about total CPU utilization which could be calculated as 100% - idle%. Totally unrelated but very useful benchmark metric is user/system CPU ratio for a specific process as a function of system load. Systems suffering from contention problems demonstrate good ratio of 80% user 20% system for low-mild load and could reverse and degrade to 20% user 80% system ratio for high load. Naturally such systems do not scale well and perform badly under heavy load. Alexander Indenbaum On 2/25/06, guy keren <[EMAIL PROTECTED]> wrote: > > On Fri, 24 Feb 2006, yahav wrote: > > > During a benchmark on our application we need to monitor the cpu usage per > > process. I tried to do it with top. > > When I'm loading the system I can see that the total cpu usage on the > > machine is increasing while no specific process show that it consumed this > > cpu. > > don't sum thins up and think this is everything. > > 1. if you have a lot of short processes created and killed, they'll effect > the "total CPU usage" but you won't see them in top since they die quicker > the top refreshes. > > 2. if you want to monirot things across time, don't use top. write a > 5-lines shell script that runs 'ps auxww', sleeps for X seconds and > repeats this in a loop. write the output to a file and then analyze it. > > neither way will allow you to catch often-created processes. for this you > might turn on process accounting (psacct is the package name, i think) > which will log every processes created on the system (when it terminates), > and the time it took to run (possibly also CPU usage - i don't remember). > this way you'll catch any created process, and wil be able to try and find > who are these invisible ghosts taking your CPU time. > > > I'm sure that the processes that run are consuming cpu. > > BTW, I can see the increasing of memory usage per process. > > > > The os version that I'm using is : (uname -a) Linux rhas4-dl360-x86-129 > > 2.6.9-5.ELsmp #1 SMP Wed Jan 5 19:29:47 EST 2005 x86_64 x86_64 x86_64 > > GNU/Linux > > unrelated to this issue - you might want to install redhat's updates on > your machine (latest kernel is 2.6.9-22.0.2.EL, i think) if it doesn't > conflict with other packages you use. > > -- > guy > > "For world domination - press 1, > or dial 0, and please hold, for the creator." -- nob o. dy > > ================================================================= > To unsubscribe, send mail to [EMAIL PROTECTED] with > the word "unsubscribe" in the message body, e.g., run the command > echo unsubscribe | mail [EMAIL PROTECTED] > > ================================================================To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
