On Thu, Oct 21, 2010 at 08:59:46AM +0200, Jens Axboe wrote: > > I don't see anything immediately wrong with your approach. I suspect > we'll need to see sysrq-t traces of the relevant processes to make a > more educated guess! I've uploaded a trace output that includes the sysrq-t trace, but I don't think it shows anything interesting. We're not hanging on any kind of loack as near as I can tell. It looks like __generic_make_request() is calling q->make_request_fn(), and this is returning without actually doing anything. http://userweb.kernel.org/~tytso/ext4-bio-patches/kvm-console-2 In this trace, I added a patch to prove that __generic_make_request() is calling __make_request (I wasn't sure what q->make_request_fn was indirecting to, so I added a brute force lookup to make sure I understood what was going on), but at one point, it just starts queuing the request, and it enters cfq, but the request never gets dispatched out. Maybe this is a failure of the plugging/unplugging mechanisms? I guess I can start putting in more brute-force printk's inside __make_request and inside the cfq scheduler to try to understand what is going on, but I'm really guessing at this point. If you have any suggestions about more elegant ways of figuring what is happening, please do let me know.... - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
