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SubjectRe: [ANNOUNCE] DSFS Network Forensic File System for Linux Patches
Bernd,

It might be helpful for someone to look at these sections of code I had
to patch in 2.6.9.
I discovered a case where the kernel scheduler will pass NULL for the
array argument
when I started hitting the extreme upper range > 200MB/S combined disk
and lan
throughput. This was running with preemptible kernel and hyperthreading
enabled.

The wheels come off in the kernel somewhere. I looked at later 2.6
kernels and there's
been some changes, but someone may get an ah ha from this fix, if there
is an underlying
problem in the kernel.

Jeff


static void dequeue_task(struct task_struct *p, prio_array_t *array)
{
- array->nr_active--;
- list_del(&p->run_list);
- if (list_empty(array->queue + p->prio))
- __clear_bit(p->prio, array->bitmap);
+ if (!array)
+ printk("WARN: prio_array was NULL in dequeue task %08X"
+ "pid-%d\n", (unsigned)p, (int)p->pid);
+
+ if (array)
+ {
+ array->nr_active--;
+ list_del(&p->run_list);
+ if (list_empty(array->queue + p->prio))
+ __clear_bit(p->prio, array->bitmap);
+ }
}


static void deactivate_task(struct task_struct *p, runqueue_t *rq)
{
- rq->nr_running--;
- if (p->state == TASK_UNINTERRUPTIBLE)
- rq->nr_uninterruptible++;
- dequeue_task(p, p->array);
- p->array = NULL;
+ if (!p->array)
+ printk("WARN: prio_array was NULL in deactivate task %08X"
+ "pid-%d\n", (unsigned)p, (int)p->pid);
+
+ if (p->array)
+ {
+ rq->nr_running--;
+ if (p->state == TASK_UNINTERRUPTIBLE)
+ rq->nr_uninterruptible++;
+ dequeue_task(p, p->array);
+ p->array = NULL;
+ }
}


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