Index: linux-2.6/block/cfq-iosched.c
===================================================================
--- linux-2.6.orig/block/cfq-iosched.c
+++ linux-2.6/block/cfq-iosched.c
@@ -174,6 +174,9 @@ struct cfq_data {
 	unsigned int cfq_slice_async_rq;
 	unsigned int cfq_slice_idle;
 	unsigned int cfq_desktop;
+	unsigned int cfq_desktop_dispatch;
+
+	unsigned long desktop_dispatch_ts;
 
 	struct list_head cic_list;
 
@@ -1283,6 +1286,7 @@ static int cfq_dispatch_requests(struct
 	struct cfq_data *cfqd = q->elevator->elevator_data;
 	struct cfq_queue *cfqq;
 	unsigned int max_dispatch;
+	unsigned long delay;
 
 	if (!cfqd->busy_queues)
 		return 0;
@@ -1297,19 +1301,26 @@ static int cfq_dispatch_requests(struct
 	/*
 	 * Drain async requests before we start sync IO
 	 */
-	if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
+	if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) {
+		cfqd->desktop_dispatch_ts = jiffies;
 		return 0;
+	}
 
 	/*
 	 * If this is an async queue and we have sync IO in flight, let it wait
 	 */
-	if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
+	if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) {
+		cfqd->desktop_dispatch_ts = jiffies;
 		return 0;
+	}
 
 	max_dispatch = cfqd->cfq_quantum;
 	if (cfq_class_idle(cfqq))
 		max_dispatch = 1;
 
+	if (cfqd->busy_queues > 1)
+		cfqd->desktop_dispatch_ts = jiffies;
+
 	/*
 	 * Does this cfqq already have too much IO in flight?
 	 */
@@ -1327,6 +1338,16 @@ static int cfq_dispatch_requests(struct
 			return 0;
 
 		/*
+		 * Don't start overloading until we've been alone for a bit.
+		 */
+		if (cfqd->cfq_desktop_dispatch) {
+			delay = cfqd->desktop_dispatch_ts + cfq_slice_sync;
+
+			if (time_before(jiffies, max_delay))
+				return 0;
+		}
+
+		/*
 		 * we are the only queue, allow up to 4 times of 'quantum'
 		 */
 		if (cfqq->dispatched >= 4 * max_dispatch)
@@ -1942,7 +1963,7 @@ static void
 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 		       struct cfq_io_context *cic)
 {
-	int old_idle, enable_idle;
+	int old_idle, enable_idle, seeky = 0;
 
 	/*
 	 * Don't idle for async or idle io prio class
@@ -1950,10 +1971,20 @@ cfq_update_idle_window(struct cfq_data *
 	if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
 		return;
 
+	if (cfqd->hw_tag) {
+		if (CIC_SEEKY(cic))
+			seeky = 1;
+		/*
+		 * If seeky or incalculable seekiness, delay overloading.
+		 */
+		if (seeky || !sample_valid(cic->seek_samples))
+			cfqd->desktop_dispatch_ts = jiffies;
+	}
+
 	enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
 
 	if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
-	    (!cfqd->cfq_desktop && cfqd->hw_tag && CIC_SEEKY(cic)))
+	    (!cfqd->cfq_desktop && seeky))
 		enable_idle = 0;
 	else if (sample_valid(cic->ttime_samples)) {
 		if (cic->ttime_mean > cfqd->cfq_slice_idle)
@@ -2483,6 +2514,9 @@ static void *cfq_init_queue(struct reque
 	cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
 	cfqd->cfq_slice_idle = cfq_slice_idle;
 	cfqd->cfq_desktop = 1;
+	cfqd->cfq_desktop_dispatch = 1;
+
+	cfqd->desktop_dispatch_ts = INITIAL_JIFFIES;
 	cfqd->hw_tag = 1;
 
 	return cfqd;
@@ -2553,6 +2587,7 @@ SHOW_FUNCTION(cfq_slice_sync_show, cfqd-
 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
 SHOW_FUNCTION(cfq_desktop_show, cfqd->cfq_desktop, 0);
+SHOW_FUNCTION(cfq_desktop_dispatch_show, cfqd->cfq_desktop_dispatch, 0);
 #undef SHOW_FUNCTION
 
 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
@@ -2585,6 +2620,7 @@ STORE_FUNCTION(cfq_slice_async_store, &c
 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
 		UINT_MAX, 0);
 STORE_FUNCTION(cfq_desktop_store, &cfqd->cfq_desktop, 0, 1, 0);
+STORE_FUNCTION(cfq_desktop_dispatch_store, &cfqd->cfq_desktop_dispatch, 0, 1, 0);
 #undef STORE_FUNCTION
 
 #define CFQ_ATTR(name) \
@@ -2601,6 +2637,7 @@ static struct elv_fs_entry cfq_attrs[] =
 	CFQ_ATTR(slice_async_rq),
 	CFQ_ATTR(slice_idle),
 	CFQ_ATTR(desktop),
+	CFQ_ATTR(desktop_dispatch),
 	__ATTR_NULL
 };
 
