confusion about kse_create()
From: Bin Ren (br260_at_cam.ac.uk)
Date: 03/09/04
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To: freebsd-current@freebsd.org Date: 09 Mar 2004 01:26:36 +0000
Hi,
After reading the MAN page and source codes for KSE, I find some parts
contradicting. Maybe the MAN page is out-dated. But I want to confirm this.
First confusion:
In KSE MAN:
----------------------------
...
To become multi-threaded, a process must first invoke kse_create(). The
kse_create() system call creates a new KSE (except for the very first
invocation; see below).
...
----------------------------
But in src/sys/sys/kern_thread.c:
----------------------------
while (newkg->kg_kses < ncpus) {
newke = kse_alloc();
bzero(&newke->ke_startzero, RANGEOF(struct kse,
ke_startzero, ke_endzero));
#if 0
mtx_lock_spin(&sched_lock);
bcopy(&ke->ke_startcopy, &newke->ke_startcopy,
RANGEOF(struct kse, ke_startcopy,
ke_endcopy));
mtx_unlock_spin(&sched_lock);
#endif
mtx_lock_spin(&sched_lock);
kse_link(newke, newkg);
sched_fork_kse(td->td_kse, newke);
/* Add engine */
kse_reassign(newke);
mtx_unlock_spin(&sched_lock);
}
--------------------------
So, apparently, with one invokation of kse_create(), new KSEs are created
so that the number of total KSEs equals the number CPUs.
Second confusion:
In KSE MAN:
-----------
as a special case, the first call to kse_create() by this initial
thread
with newgroup equal to zero does not create a new KSE; instead, it
simply
associates the current KSE with the supplied KSE mailbox, and no
immedi-
ate upcall results. However, an upcall will be triggered the next time
the thread blocks and the required conditions are met.
-----------
In the source codes for kse_create(), I cannot find the corresponding lines.
What am I missing here?
Thanks so much in advance!
-- Bin
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