Date: Sun, 6 Mar 2005 19:35:14 -0800 From: "Ashwin Chandra" <ashcs@ucla.edu> To: <freebsd-hackers@freebsd.org> Subject: taking a process and all associated threads off the run queue Message-ID: <000801c522c6$ad04a940$abe243a4@ash>
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Hi all,
I am trying to modify the scheduler to take off some processes (such as =
those generated by a forkbomb ... malicious) off the run queue. I have =
been looking into the scheduler and proc.h and see there is one way by =
putting threads on the 'suspension' queue. I am not sure if this is the =
same thing. But anyway, I modified sched_cpu in sched_4bsd.c to look =
something like this:
=20
FOREACH_THREAD_IN_PROC(p, td)
{
if(p->p_km_switch =3D=3D P_NON_RUN)
{
if( !TD_IS_SUSPENDED(td) )
{
//thread_suspend_one(td);
printf("suspending thread associated with =
%s\n", td->td_ksegrp->kg_proc->p_comm);
TD_SET_SUSPENDED(td);
}
}
else if(p->p_km_switch =3D=3D P_RUN)
{
if(TD_IS_SUSPENDED(td))
{
//thread_unsuspend_one(td);
printf("clearing suspending thread =
associated with %s\n", td->td_ksegrp->kg_proc->p_comm);
TD_CLR_SUSPENDED(td);
}
}
}
the p_km_switch turns on when a process exceeds a certain threshold of =
memory usage and context switching. If the threads associated with this =
process are suspended, and the system becomes less loady, then they are =
unsuspended (The P_RUN flag is set externally). So I tried this out, and =
it seems to sort of work although when I print out the p->p_suspcount, =
it says its 0, so I am not sure if this is even working right.
Im sure you guys know the scheduler much better than I do. What would be =
the best way to modify the scheduler so that given a certain NON_RUN =
flag I can pretty much take a process of the run queue and then later =
put it back on when the system is less loaded?
Thanks a lot,
Ash
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