linux/fs/gfs2/locking/dlm/thread.c
Steven Whitehouse 1bdad60633 [GFS2] Remove remote lock dropping code
There are several reasons why this is undesirable:

 1. It never happens during normal operation anyway
 2. If it does happen it causes performance to be very, very poor
 3. It isn't likely to solve the original problem (memory shortage
    on remote DLM node) it was supposed to solve
 4. It uses a bunch of arbitrary constants which are unlikely to be
    correct for any particular situation and for which the tuning seems
    to be a black art.
 5. In an N node cluster, only 1/N of the dropped locked will actually
    contribute to solving the problem on average.

So all in all we are better off without it. This also makes merging
the lock_dlm module into GFS2 a bit easier.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-06-27 09:39:44 +01:00

68 lines
1.4 KiB
C

/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include "lock_dlm.h"
static inline int no_work(struct gdlm_ls *ls)
{
int ret;
spin_lock(&ls->async_lock);
ret = list_empty(&ls->submit);
spin_unlock(&ls->async_lock);
return ret;
}
static int gdlm_thread(void *data)
{
struct gdlm_ls *ls = (struct gdlm_ls *) data;
struct gdlm_lock *lp = NULL;
while (!kthread_should_stop()) {
wait_event_interruptible(ls->thread_wait,
!no_work(ls) || kthread_should_stop());
spin_lock(&ls->async_lock);
if (!list_empty(&ls->submit)) {
lp = list_entry(ls->submit.next, struct gdlm_lock,
delay_list);
list_del_init(&lp->delay_list);
spin_unlock(&ls->async_lock);
gdlm_do_lock(lp);
spin_lock(&ls->async_lock);
}
spin_unlock(&ls->async_lock);
}
return 0;
}
int gdlm_init_threads(struct gdlm_ls *ls)
{
struct task_struct *p;
int error;
p = kthread_run(gdlm_thread, ls, "lock_dlm");
error = IS_ERR(p);
if (error) {
log_error("can't start lock_dlm thread %d", error);
return error;
}
ls->thread = p;
return 0;
}
void gdlm_release_threads(struct gdlm_ls *ls)
{
kthread_stop(ls->thread);
}