[Iscsitarget-devel] [patch] wthread gentle wake_up

[Ross S. W. W. <RW...@me...>]

This patch prevents continuous wake_ups from being called after
the first.

It also spreads the processing more evenly between threads by
performing an 'if' instead of a 'while' in the processing loop.

Signed-off-by: Ross Walker

Index: kernel/wthread.c
===================================================================
--- kernel/wthread.c	(revision 328)
+++ kernel/wthread.c	(working copy)
@@ -32,7 +32,8 @@
 
 	atomic_inc(&cmnd->conn->nr_busy_cmnds);
 
-	wake_up(&info->wthread_sleep);
+	if (!test_and_set_bit(D_DATA_READY, &info->flags))
+		wake_up(&info->wthread_sleep);
 }
 
 static struct iscsi_cmnd * get_ready_cmnd(struct worker_thread_info *info)
@@ -78,10 +79,13 @@
 
 	add_wait_queue(&info->wthread_sleep, &wait);
 
-	__set_current_state(TASK_RUNNING);
 	do {
-		while (!list_empty(&info->work_queue) &&
-		       (cmnd = get_ready_cmnd(info))) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (!test_and_clear_bit(D_DATA_READY, &info->flags))
+			schedule();
+		__set_current_state(TASK_RUNNING);
+
+		if ((cmnd = get_ready_cmnd(info))) {
 			conn = cmnd->conn;
 			if (cmnd_tmfabort(cmnd))
 				cmnd_release(cmnd, 1);
@@ -90,12 +94,6 @@
 			assert(conn);
 			atomic_dec(&conn->nr_busy_cmnds);
 		}
-
-		set_current_state(TASK_INTERRUPTIBLE);
-		if (list_empty(&info->work_queue))
-			schedule();
-
-		__set_current_state(TASK_RUNNING);
 	} while (!kthread_should_stop());
 
 	remove_wait_queue(&info->wthread_sleep, &wait);
Index: kernel/iscsi.h
===================================================================
--- kernel/iscsi.h	(revision 328)
+++ kernel/iscsi.h	(working copy)
@@ -85,6 +85,7 @@
 };
 
 struct worker_thread_info {
+	unsigned long flags;
 	spinlock_t wthread_lock;
 
 	u32 nr_running_wthreads;
@@ -97,6 +98,11 @@
 	struct io_context *wthread_ioc;
 };
 
+enum daemon_state_bit {
+	D_ACTIVE,
+	D_DATA_READY,
+};
+
 struct iscsi_cmnd;
 
 struct target_type {
Index: kernel/nthread.c
===================================================================
--- kernel/nthread.c	(revision 328)
+++ kernel/nthread.c	(working copy)
@@ -15,11 +15,6 @@
 #include "iscsi_dbg.h"
 #include "digest.h"
 
-enum daemon_state_bit {
-	D_ACTIVE,
-	D_DATA_READY,
-};
-
 void __nthread_wakeup(struct network_thread_info *info)
 {
 	set_bit(D_DATA_READY, &info->flags);

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