Re: [2.4.17/18pre] VM and swap - it's really unusable

Roman Zippel
2002-01-14T16:19:57Z

Hi,

On Mon, 14 Jan 2002, Rik van Riel wrote:

> Without preemption task C would not have been preempted and it would
> have released the lock much sooner, meaning task A could have gotten
> the resource earlier.

Define "much sooner", nobody disputes that low priority tasks can be
delayed, that's actually the purpose of both patches.

> Using the low latency patch we'd insert some smart code into the
> algorithm so task A also releases the lock before rescheduling.

Could you please show me that "smart code"?

> Before you say this thing never happens in practice, I ran into
> this thing in real life with the SCHED_IDLE patch. In fact, this
> problem was so severe it convinced me to abandon SCHED_IDLE ;))

SCHED_IDLE is something completely different than preeempt. Rik, do I
really have to explain the difference?

bye, Roman