Re: sluggish system responsiveness under higher IO load

[Jens Axboe <axboe@suse.de>]

On Sun, Aug 06 2006, Matthias Dahl wrote:
> > I'd suggest that you generate a kernel profile while the sluggishness is
> > happening.
> 
> Done...
> 
> profile 1: (emerge of three huge packages which caused quite some IO)

Can you see if this makes any difference whatsoever?

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 61d6b3c..ed6a30e 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3422,6 +3422,7 @@ #endif /* CONFIG_HOTPLUG_CPU */
 
 void blk_complete_request(struct request *req)
 {
+#if 0
 	struct list_head *cpu_list;
 	unsigned long flags;
 
@@ -3434,6 +3435,14 @@ void blk_complete_request(struct request
 	raise_softirq_irqoff(BLOCK_SOFTIRQ);
 
 	local_irq_restore(flags);
+#else
+	unsigned long flags;
+	request_queue_t *q = req->q;
+
+	local_irq_save(flags);
+	q->softirq_done_fn(req);
+	local_irq_restore(flags);
+#endif
 }
 
 EXPORT_SYMBOL(blk_complete_request);

-- 
Jens Axboe