Re: [PATCH] [request for inclusion] Realtime LSM

Jack O'Quin
2005-01-15T23:02:24Z

Ingo Molnar <mingo@elte.hu> writes:

> * Jack O'Quin <joq@io.com> wrote:
>
>> OK, I reran with just 5 processes reniced from -10 to -5. On my
>> system they were: events, khelper, kblockd, aio and reiserfs. In
>> addition, I reniced loop0 from -20 to -5.
>
>> One major problem: this `nice --20' hack affects every thread, not
>> just the critical realtime ones. That's not what we want. Audio
>> applications make very conscious choices which threads run with high
>> priority and which do not.
>
> how much did this problem affect your test? Could the source of the 500
> msec delays be the non-highprio components of the test that somehow
> became nice --20?

Some interference is definitely possible. But, the test does not
involve any graphical interface, so I'd expect that to be small.
Looking at jack_test3_client.cpp, the main thread just does a sleep()
while the process cycle is running.

Still, it's hard to be sure.

Probably, the best way to tell would be patching JACK so it uses
nice(-20) instead of pthread_setschedparam() for the realtime threads.
As a hack, that looks easy. I'll build a working directory with just
that change, so we can experiment with it better.
--
joq