[Linux-ia64] Re: web page on O(1) scheduler

Mike Galbraith
2003-05-22T16:25:54Z

At 11:52 AM 5/22/2003 +0200, Mike Galbraith wrote:
>At 10:56 AM 5/21/2003 -0700, David Mosberger wrote:
>> >>>>> On Wed, 21 May 2003 11:26:31 +0200, Mike Galbraith <efault@gmx.de>
>> said:
>>
>> Mike> The page mentions persistent starvation. My own explorations
>> Mike> of this issue indicate that the primary source is always
>> Mike> selecting the highest priority queue.
>>
>>My working assumption is that the problem is a bug with the dynamic
>>prioritization. The task receiving the signals calls sleep() after
>>handling a signal and hence it's dynamic priority should end up higher
>>than the priority of the task sending signals (since the sender never
>>relinquishes the CPU voluntarily).
>>
>>However, I haven't actually had time to look at the relevant code, so
>>I may be missing something. If you understand the issue better,
>>please explain to me why this isn't a dynamic priority issue.
>
>You're right, it looks like a corner case.

Out of curiosity, is someone hitting that with a real program?

-Mike

aside:
if so, I suppose nano-ticks may be needed. rounding up gave us too many
"nano-ticks", and was the first problem with irman, which brought round
down into activate_task(). now, test-starve.c appears, and it turns out to
be too many nano-ticks _missing_. (rounding up doesn't "fix" that one btw
[too fast], but what I did to demonstrate the problem does re-break irman
rather nicely:)