Re: Real-Time Preemption and RCU

[Kyle Moffett]

On Mar 19, 2005, at 11:31, Ingo Molnar wrote:
> > What about allowing only as many concurrent readers as there are CPUs?
>
> since a reader may be preempted by a higher prio task, there is no
> linear relationship between CPU utilization and the number of readers
> allowed. You could easily end up having all the nr_cpus readers
> preempted on one CPU. It gets pretty messy

One solution I can think of, although it bloats memory usage for 
many-way
boxen, is to just have a table in the rwlock with one entry per cpu.  
Each
CPU would get one concurrent reader, others would need to sleep

Cheers,
Kyle Moffett

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