nfs:nfs_async_timeout

Description

Controls the duration of time that threads, which execute asynchronous I/O requests, sleep with nothing to do before exiting. When there are no more requests to execute, each thread goes to sleep. If no new requests come in before this timer expires, the thread wakes up and exits. If a request does arrive, a thread is woken up to execute requests until there are none again, and then goes back to sleep waiting for another request to arrive, or for the timer to expire.

Data Type

Integer (32–bit)

Default

6000 (1 minute expressed as 60 sec * 100Hz)

Range

0 to 2³¹ - 1

Units

Hz (Typically, the clock runs at 100Hz)

Dynamic?

Yes

Validation

None. However, setting this parameter to a non-positive value has the affect of having these threads exit as soon as there are no requests in the queue for them to process.

When to Change

If the behavior of applications in the system is known precisely and the rate of asynchronous I/O requests can be predicted, it might be possible to tune this parameter to optimize performance slightly in either of the following ways:

• By making the threads expire more quickly, thus freeing up kernel resources more quickly,

• Or, by making them expire more slowly, thus avoiding thread create and destroy overhead.

Stability Level

Evolving