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Code Issues Releases Activity

- In kseq_transfer() return if smp has not been started.

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- In sched_add(), do the idle check prior to the transfer check so that we
   don't try to transfer load from an idle cpu.  This fixes panics caused by
   IPIs on UP machines running SMP kernels.

Reported/Debugged by:	seanc
This commit is contained in:
Jeff Roberson 2003-12-20 14:03:14 +00:00
parent 9b5f6f623d
commit 670c524f08
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=123685
1 changed files with 14 additions and 9 deletions
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23
sys/kern/sched_ule.c
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@ -729,9 +729,18 @@ kseq_transfer(struct kseq *kseq, struct kse *ke, int class)
struct kseq_group *ksg;
int cpu;
if (smp_started == 0)
return (0);
cpu = 0;
ksg = kseq->ksq_group;
/*
* If there are any idle groups, give them our extra load. The
* threshold at which we start to reassign kses has a large impact
* on the overall performance of the system. Tuned too high and
* some CPUs may idle. Too low and there will be excess migration
* and context swiches.
*/
/*
* XXX This ksg_transferable might work better if we were checking
* against a global group load. As it is now, this prevents us from
@ -1588,15 +1597,9 @@ sched_add(struct thread *td)
return;
}
/*
* If there are any idle groups, give them our extra load. The
* threshold at which we start to reassign kses has a large impact
* on the overall performance of the system. Tuned too high and
* some CPUs may idle. Too low and there will be excess migration
* and context swiches.
* If we had been idle, clear our bit in the group and potentially
* the global bitmap. If not, see if we should transfer this thread.
*/
if (kseq->ksq_load > 1 && KSE_CAN_MIGRATE(ke, class))
if (kseq_transfer(kseq, ke, class))
return;
if ((class == PRI_TIMESHARE || class == PRI_REALTIME) &&
(kseq->ksq_group->ksg_idlemask & PCPU_GET(cpumask)) != 0) {
/*
@ -1610,7 +1613,9 @@ sched_add(struct thread *td)
* Now remove ourselves from the group specific idle mask.
*/
kseq->ksq_group->ksg_idlemask &= ~PCPU_GET(cpumask);
}
} else if (kseq->ksq_load > 1 && KSE_CAN_MIGRATE(ke, class))
if (kseq_transfer(kseq, ke, class))
return;
#endif
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;