Hey, On Tue, Apr 09, 2013 at 04:32:28PM -0400, Mikulas Patocka wrote: > > and we probably need to change that to bio_associate_task(). > > Generally, we shouldn't associate bios with "current" task in device > mapper targets. For example suppose that we have two stacked dm-crypt > targets:
It only follows the first association so it doesn't matter how many layers it goes through. That said, yeah, there could be situations where @task is availalbe but the bio's already in the hand of a different task. If that's the case, change it to associate_task(@task). > It doesn't work because device mapper on the underlying layers ignores > bi_ioc and bi_css. > > If I make device mapper forward bi_ioc and bi_css to outgoing bios, it > improves performance (from 2:30 to 1:30), but it is still far from > perfect. For testing, copying bi_ioc and bi_css directly is fine but please add another interface to copy those for the actual code. Say, bio_copy_association(@to_bio, @from_bio) or whatever. As for the performance loss, I'm somewhat confident in saying the remaining difference would be from ignoring plugging boundaries. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
