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scst: Speed up command thread creation

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Avoid hitting a 50 ms delay during thread creation.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@6493 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2015-09-01 02:29:02 +00:00
parent 35bca71f0c
commit 0a4bce0392
4 changed files with 11 additions and 14 deletions
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1
scst/include/scst.h
View File

@@ -2271,6 +2271,7 @@ struct scst_cmd_threads {
int io_context_refcnt;
bool io_context_ready;
wait_queue_head_t ioctx_wq;
/* io_context_mutex protects io_context and io_context_refcnt. */
struct mutex io_context_mutex;

14
scst/src/scst_lib.c
View File

@@ -4495,6 +4495,7 @@ struct scst_acg *scst_tgt_find_acg(struct scst_tgt *tgt, const char *name)
static struct scst_tgt_dev *scst_find_shared_io_tgt_dev(
struct scst_tgt_dev *tgt_dev)
{
struct scst_cmd_threads *a;
struct scst_tgt_dev *res = NULL;
struct scst_session *sess = tgt_dev->sess;
struct scst_acg *acg = tgt_dev->acg_dev->acg;
@@ -4566,21 +4567,16 @@ out:
return res;
found:
if (t->active_cmd_threads == &scst_main_cmd_threads) {
res = t;
res = t;
a = t->active_cmd_threads;
if (a == &scst_main_cmd_threads) {
TRACE_DBG("Going to share async IO context %p (res %p, "
"ini %s, dev %s, grouping type %d)",
t->aic_keeper->aic, res, t->sess->initiator_name,
t->dev->virt_name,
t->acg_dev->acg->acg_io_grouping_type);
} else {
res = t;
if (!*(volatile bool *)&res->active_cmd_threads->io_context_ready) {
TRACE_DBG("IO context for t %p not yet "
"initialized, waiting...", t);
msleep(100);
goto found;
}
wait_event(a->ioctx_wq, a->io_context_ready);
smp_rmb();
TRACE_DBG("Going to share IO context %p (res %p, ini %s, "
"dev %s, cmd_threads %p, grouping type %d)",

8
scst/src/scst_main.c
View File

@@ -1929,11 +1929,8 @@ out_wait:
* Wait for io_context gets initialized to avoid possible races
* for it from the sharing it tgt_devs.
*/
while (!*(volatile bool *)&cmd_threads->io_context_ready) {
TRACE_DBG("Waiting for io_context for cmd_threads %p "
"initialized", cmd_threads);
msleep(50);
}
wait_event(cmd_threads->ioctx_wq,
cmd_threads->io_context_ready);
smp_rmb();
}
@@ -2182,6 +2179,7 @@ void scst_init_threads(struct scst_cmd_threads *cmd_threads)
spin_lock_init(&cmd_threads->cmd_list_lock);
INIT_LIST_HEAD(&cmd_threads->active_cmd_list);
init_waitqueue_head(&cmd_threads->cmd_list_waitQ);
init_waitqueue_head(&cmd_threads->ioctx_wq);
INIT_LIST_HEAD(&cmd_threads->threads_list);
mutex_init(&cmd_threads->io_context_mutex);
spin_lock_init(&cmd_threads->thr_lock);

2
scst/src/scst_targ.c
View File

@@ -5010,6 +5010,8 @@ int scst_cmd_thread(void *arg)
scst_ioctx_get(p_cmd_threads);
wake_up_all(&p_cmd_threads->ioctx_wq);
spin_lock_irq(&p_cmd_threads->cmd_list_lock);
while (!kthread_should_stop()) {
wait_event_locked(p_cmd_threads->cmd_list_waitQ,