Re: [Lse-tech] Re: [PATCH for 2.5] preemptible kernel

From: yodaiken@fsmlabs.com
Date: Wed Apr 11 2001 - 00:22:13 EST


On Tue, Apr 10, 2001 at 09:08:16PM -0700, Paul McKenney wrote:
> > Disabling preemption is a possible solution if the critical section is
> short
> > - less than 100us - otherwise preemption latencies become a problem.
>
> Seems like a reasonable restriction. Of course, this same limit applies
> to locks and interrupt disabling, right?

So supposing 1/2 us per update
        lock process list
                for every process update pgd
        unlock process list

is ok if #processes < 200, but can cause some unspecified system failure
due to a dependency on the 100us limit otherwise?

And on a slower machine or with some heavy I/O possibilities ....

We have a tiny little kernel to worry about inRTLinux and it's quite
hard for us to keep track of all possible delays in such cases. How's this
going to work for Linux?

        

-- 
---------------------------------------------------------
Victor Yodaiken 
Finite State Machine Labs: The RTLinux Company.
 www.fsmlabs.com  www.rtlinux.com

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