Messages in this thread |  | | Date | Fri, 10 Feb 2012 16:48:49 +0800 | Subject | Re: [PATCH] block: strip out locking optimization in put_io_context() | From | Shaohua Li <> |
| |
2012/2/10 Shaohua Li <shli@kernel.org>: > 2012/2/10 Tejun Heo <tj@kernel.org>: >> Hello, Shaohua. >> >> Can you please test the following one? It's probably the simplest >> version w/o RCU and wq deferring. RCUfying isn't too bad but I'm >> still a bit hesitant because RCU coverage needs to be extended to >> request_queue via conditional synchronize_rcu() in queue exit path >> (can't enforce delayed RCU free on request_queues and unconditional >> synchronize_rcu() may cause excessive delay during boot for certain >> configurations). It now can be done in the block core layer proper so >> it shouldn't be as bad tho. If this too flops, I'll get to that. > doesn't work. I added trace in the schedule_work code path of put_io_context, which runs very rare. So it's not lock contention for sure. Sounds the only difference between the good/bad cases is the good case runs with rcu_lock_read/rcu_read_unlock. I also checked slab info, the cfq related slab doesn't use too many memory, unlikely because rcu latency uses too many memory. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |