-1
votes
0answers
12 views

Modifying CPU Scheduling algo in linux kernel [on hold]

I know how CPU Schedulers work in different linux distributions. I want to see the code for this and modify the CPU Scheduling to optimize it for background processes. But I never worked on kernel ...
1
vote
1answer
40 views

Can a real-time process exist in the 'expired' queue of linux kernel?

In the Linux kernel 2.4: Real-time processes are given a priority of 0-99 and they co-exist in the ready queue along with the nice processes (who's priority goes between 100 and 139). But real-time ...
7
votes
1answer
293 views

How is nice working?

sched_setscheduler says : All scheduling is preemptive: if a process with a higher static priority becomes ready to run, the currently running process will be preempted and ...
2
votes
0answers
149 views

how to stop kernel threads preempting real time user space processes?

I created some processes in user space and tried to visualize its working in kernelshark with the trace recorded using trace-cmd. But kernel processes like the ones shown below are preempting my ...
2
votes
2answers
486 views

Can system calls be interrupted?

Please comment on the following sentence: On the standard Linux kernel without the rt patch, interrupts can't interrupt ongoing system calls. The reason why our machine doesn't stop working ...
2
votes
1answer
171 views

Are time interrupts always followed by a scheduler call?

When a timer interrupt occurred the ISR is called to service the interrupt. Is it okay to assume that every timer interrupt ends with a call to the scheduler on which process should continue running ...
3
votes
2answers
6k views

What does “INFO: task XXX blocked for more than 120 seconds” exactly mean on Linux?

I had this message in my kernel log : INFO: task XXX blocked for more than 120 seconds. I would like to know what it means technically: under what conditions does the kernel display this message about ...
23
votes
1answer
2k views

High CPU usage with CFS?

I asked a previous question to try and isolate the source of an increase in CPU usage when moving an application from RHEL 5 to RHEL 6. The analysis that I did for that seems to indicate that it is ...
8
votes
1answer
3k views

Isolating cause of higher CPU usage on RHEL 6 vs RHEL 5

I'm currently looking to move our system from RHEL 5 to RHEL 6, but I've run into a snag with unexpectedly high CPU usage on the RHEL 6 machines. It appears that this may be due at least in some part ...