On Mon, Aug 02, 2010 at 07:52:29PM -0700, john stultz wrote: > With the non-vfs scalability patched kernels, we see that the j_state > lock and atomic changes pull start_this_handle out of the top contender > handle, but there is still quite a large amount of contention on the > dput paths. > > So yea, the change does help, but its just not the top cause of > contention when aren't using the vfs patches, so we don't see as much > benefit at this point. Great, thanks for uploading the lockstats. Since dbench is so metadata heavy, it makes a lot of sense that further jbd2 optimizations probably won't make much difference until the VFS bottlenecks can be solved. Other benchmarks, such as the FFSB benchmarks used by Steven Pratt and Eric Whitney, would probably show more of a difference. In any case, I've just sent two more patches which completely remove any exclusive spinlocks from start_this_handle() by converting j_state_lock to a rwlock_t, and dropping the need to take t_handle_lock. This will add more cache line bouncing, so on NUMA workloads this may make things worse, but I guess we'll have to see. Anyone have access to an SGI Altix? I'm assuming the old Sequent NUMA boxes are long gone by now... - 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
