diff options
| -rw-r--r-- | Documentation/block/null_blk.txt | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/Documentation/block/null_blk.txt b/Documentation/block/null_blk.txt index 9e1b047fd13d..5603dad5534b 100644 --- a/Documentation/block/null_blk.txt +++ b/Documentation/block/null_blk.txt | |||
| @@ -18,7 +18,7 @@ The following instances are possible: | |||
| 18 | - Bio-based. IO requests are submitted directly to the device driver. | 18 | - Bio-based. IO requests are submitted directly to the device driver. |
| 19 | - Directly accepts bio data structure and returns them. | 19 | - Directly accepts bio data structure and returns them. |
| 20 | 20 | ||
| 21 | All of them has a completion queue for each core in the system. | 21 | All of them have a completion queue for each core in the system. |
| 22 | 22 | ||
| 23 | II. Module parameters applicable for all instances: | 23 | II. Module parameters applicable for all instances: |
| 24 | 24 | ||
| @@ -30,7 +30,7 @@ queue_mode=[0-2]: Default: 2-Multi-queue | |||
| 30 | 2: Multi-queue. | 30 | 2: Multi-queue. |
| 31 | 31 | ||
| 32 | home_node=[0--nr_nodes]: Default: NUMA_NO_NODE | 32 | home_node=[0--nr_nodes]: Default: NUMA_NO_NODE |
| 33 | Selects what socket the data structures is allocated from. | 33 | Selects what CPU node the data structures are allocated from. |
| 34 | 34 | ||
| 35 | gb=[Size in GB]: Default: 250GB | 35 | gb=[Size in GB]: Default: 250GB |
| 36 | The size of the device reported to the system. | 36 | The size of the device reported to the system. |
| @@ -38,34 +38,34 @@ gb=[Size in GB]: Default: 250GB | |||
| 38 | bs=[Block size (in bytes)]: Default: 512 bytes | 38 | bs=[Block size (in bytes)]: Default: 512 bytes |
| 39 | The block size reported to the system. | 39 | The block size reported to the system. |
| 40 | 40 | ||
| 41 | nr_devices=[Num. devices]: Default: 2 | 41 | nr_devices=[Number of devices]: Default: 2 |
| 42 | Number of block devices instantiated. They are instantiated as /dev/nullb0, | 42 | Number of block devices instantiated. They are instantiated as /dev/nullb0, |
| 43 | etc. | 43 | etc. |
| 44 | 44 | ||
| 45 | irq_mode=[0-2]: Default: Soft-irq | 45 | irq_mode=[0-2]: Default: 1-Soft-irq |
| 46 | The completion mode used for completing IOs to the block-layer. | 46 | The completion mode used for completing IOs to the block-layer. |
| 47 | 47 | ||
| 48 | 0: None. | 48 | 0: None. |
| 49 | 1: Soft-irq. Uses ipi to complete IOs across sockets. Simulates the overhead | 49 | 1: Soft-irq. Uses IPI to complete IOs across CPU nodes. Simulates the overhead |
| 50 | when IOs are issued from another socket than the home the device is | 50 | when IOs are issued from another CPU node than the home the device is |
| 51 | connected to. | 51 | connected to. |
| 52 | 2: Timer: Waits a specific period (completion_nsec) for each IO before | 52 | 2: Timer: Waits a specific period (completion_nsec) for each IO before |
| 53 | completion. | 53 | completion. |
| 54 | 54 | ||
| 55 | completion_nsec=[Num. ns]: Default: 10.000ns | 55 | completion_nsec=[ns]: Default: 10.000ns |
| 56 | Combined with irq_mode=2 (timer). The time each completion event must wait. | 56 | Combined with irq_mode=2 (timer). The time each completion event must wait. |
| 57 | 57 | ||
| 58 | submit_queues=[0..nr_cpus]: | 58 | submit_queues=[0..nr_cpus]: |
| 59 | The number of submission queues attached to the device driver. If unset, it | 59 | The number of submission queues attached to the device driver. If unset, it |
| 60 | defaults to 1 on single-queue and bio-based instances. For multi-queue, | 60 | defaults to 1 on single-queue and bio-based instances. For multi-queue, |
| 61 | its ignored when use_per_node_hctx module parameter is 1. | 61 | it is ignored when use_per_node_hctx module parameter is 1. |
| 62 | 62 | ||
| 63 | hw_queue_depth=[0..qdepth]: Defaults: 64 | 63 | hw_queue_depth=[0..qdepth]: Default: 64 |
| 64 | The hardware queue depth of the device. | 64 | The hardware queue depth of the device. |
| 65 | 65 | ||
| 66 | III: Multi-queue specific parameters | 66 | III: Multi-queue specific parameters |
| 67 | 67 | ||
| 68 | use_per_node_hctx=[0/1]: Defaults: 1 | 68 | use_per_node_hctx=[0/1]: Default: 1 |
| 69 | If 1, the multi-queue block layer is instantiated with a hardware dispatch | 69 | If 1, the multi-queue block layer is instantiated with a hardware dispatch |
| 70 | queue for each CPU node in the system. If 0, it is instantiated with the | 70 | queue for each CPU node in the system. If 0, it is instantiated with the |
| 71 | number of queues defined in the submit_queues parameter. | 71 | number of queues defined in the submit_queues parameter. |
