/*
 * Oracle Linux DTrace.
 * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
 * Licensed under the Universal Permissive License v 1.0 as shown at
 * http://oss.oracle.com/licenses/upl.
 */

#pragma D option quiet
#pragma D option nspec=4
#pragma D option specsize=100k

int maxlen;
int spec[int];

sched:::enqueue
{
	this->len = ++qlen[this->cpu = args[2]->cpu_id];
	in[args[0]->pr_addr] = timestamp;
}

sched:::enqueue
/this->len > maxlen && spec[this->cpu]/
{
	/*
	 * There is already a speculation for this CPU.  We just set a new
	 * record, so we'll discard the old one.
	 */
	discard(spec[this->cpu]);
}

sched:::enqueue
/this->len > maxlen/
{
	/*
	 * We have a winner.  Set the new maximum length and set the timestamp
	 * of the longest length.
	 */
	maxlen = this->len;
	longtime[this->cpu] = timestamp;	

	/*
	 * Now start a new speculation, and speculatively trace the length.
	 */
	this->spec = spec[this->cpu] = speculation();
	speculate(this->spec);
	printf("Run queue of length %d:\n", this->len);
}

sched:::dequeue
/(this->in = in[args[0]->pr_addr]) &&
    this->in <= longtime[this->cpu = args[2]->cpu_id]/
{
	speculate(spec[this->cpu]);
	printf("  %d/%d (%s)\n", 
	    args[1]->pr_pid, args[0]->pr_lwpid,
	    stringof(args[1]->pr_fname));
}

sched:::dequeue
/qlen[args[2]->cpu_id]/
{
	in[args[0]->pr_addr] = 0;
	this->len = --qlen[args[2]->cpu_id];
}

sched:::dequeue
/this->len == 0 && spec[this->cpu]/
{
	/*
	 * We just processed the last thread that was enqueued at the time
	 * of longest length; commit the speculation, which by now contains
	 * each thread that was enqueued when the queue was longest.
	 */
	commit(spec[this->cpu]);
	spec[this->cpu] = 0;
}
