Two scsi-mq tips: 1. Several people have been wondering how to enable scsi-mq. Add this to your kernel command line (e.g., in /boot/grub/grub.conf if using grub-1): scsi_mod.use_blk_mq=Y One way to tell it is enabled is to notice these directories being created in sysfs: /sys/block/sda/mq 2. If you're running kernel-3.17.0rc1 and scsi-mq, you may want to pick up this patch from Tejun in Jens' linux-block tree: http://git.kernel.dk/?p=linux-block.git;a=commit;h=cddd5d17642cc6881352732693c2ae6930e9ce65 to avoid errors like this on device removal: [ 1454.516816] ------------[ cut here ]------------ [ 1454.518348] WARNING: CPU: 0 PID: 4157 at lib/percpu-refcount.c:179 percpu_ref_kill_and_confirm+0x69/0x80() [ 1454.521464] percpu_ref_kill() called more than once! ... [ 1454.553623] Call Trace: [ 1454.554707] [<ffffffff815af44f>] dump_stack+0x49/0x62 [ 1454.556349] [<ffffffff81055f6c>] warn_slowpath_common+0x8c/0xc0 [ 1454.558487] [<ffffffff81056056>] warn_slowpath_fmt+0x46/0x50 [ 1454.560565] [<ffffffff812aa1b9>] percpu_ref_kill_and_confirm+0x69/0x80 [ 1454.562654] [<ffffffff8127a753>] blk_mq_freeze_queue+0x53/0xf0 [ 1454.565179] [<ffffffff8127ae56>] blk_mq_free_queue+0x26/0x140 [ 1454.567572] [<ffffffff81272da8>] blk_release_queue+0x88/0xe0 [ 1454.569465] [<ffffffff81299972>] kobject_cleanup+0x82/0x1c0 [ 1454.571316] [<ffffffff81299abd>] kobject_release+0xd/0x10 [ 1454.573289] [<ffffffff81299af1>] kobject_put+0x31/0x70 [ 1454.574937] [<ffffffff8126e8d5>] blk_put_queue+0x15/0x20 [ 1454.576651] [<ffffffff813dfaa4>] scsi_device_dev_release_usercontext+0xc4/0x120 [ 1454.579026] [<ffffffff8106cc7d>] execute_in_process_context+0x5d/0x70 [ 1454.581442] [<ffffffff813df9dc>] scsi_device_dev_release+0x1c/0x20 [ 1454.583502] [<ffffffff813a46d8>] device_release+0x38/0xb0 [ 1454.585483] [<ffffffff81299972>] kobject_cleanup+0x82/0x1c0 [ 1454.587547] [<ffffffff81299abd>] kobject_release+0xd/0x10 [ 1454.589307] [<ffffffff81299af1>object_put+0x31/0x70 [ 1454.691222] [<ffffffff813a42f7>] put_device+0x17/0x20 [ 1454.692843] [<ffffffff813ce8f5>] scsi_device_put+0x45/0x60 Both Douglas Gilbert and I ran into that. --- Rob Elliott HP Server Storage -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
