[linux-audio-user] realtime parameters ignored at Gentoo startup

Jack O'Quin joq at io.com
Wed Mar 9 13:32:40 EST 2005

"Andreas Kuckartz" <A.Kuckartz at ping.de> writes:

> Jack O'Quin wrote:
>> > What's the significance of using mlock?
>> It enables programs to lock memory using the mlock() and mlockall()
>> system calls.
> What is the practical difference if mlock() and mlockall() system calls are
> used?

Often it makes no difference at all.  That's why it's an option.  :-)

Programs like JACK ordinarily try to lock memory when running with the
--realtime option to prevent data accessed by realtime-critical code
being paged out.  If that happens XRUNS will surely ensue, but it
usually doesn't because these pages tend to be accessed regularly
enough to escape the VM page replacement algorithm.  But, without
mlock(), there is no guarantee.

If you decide to specify mlock=0, you should probably also specify the
`jackd -m' (--no-mlock) option.

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