tahmid04 / xv6-scheduling-july-2022 Goto Github PK

Dear Sir

As part of our assignment, we were asked to give processes a default ticket value of 1. I have assumed this includes init, the very first process, and have assigned a ticket value of 1 to it. However, once init forks sh, init is always in the sleep state (as seen by procdump), and never ticks again for as long as xv6 runs. If it does not ever run again, it will never use its ticket.

We were asked to reinstate ticket values only when all processes have zero tickets. How do we deal with this apparent contradiction? Or have I missed anything?

Thanks in advance
Showvik
1805068

If I have multiple testticket processes with a moderately high number of tickets (~10), it takes a long time for the shell process to be be selected by the scheduler. So there's a significant waiting time in between when I can input shell commands. I believe its because shell has a default ticket count of 1, although there could be something wrong in my implementation. Please advise.

Also, my implementation of testticket contains an infinite loop at the end so if I run something like:
testticket 5 &; testticket 4 &; testticket 3

The very last process testticket 3 continues running and doesn't return to shell. A possible workaround is having a redundant call at the end like:
testticket 5 &; testticket 4 &; testticket 3 &; echo 1
Will this be acceptable?

Sir, should we consider all process having a ticket or only the runnable ones during probability calculation?

Sir we are instructed to pass the parent's ticket number to child's ticket number when fork() called, should it be the parent's Initial ticket number, or the Current ticket number? Its not clearly mentioned in the specs.

Thanks

Md Toki Tahmid
1805030

I found argaddr() in system call fstat() though which seems to pass pointers from user to kernel.