Re: SRCU: Number of outstanding callbacks

["Dmitriy V\\'jukov" <dvyukov@gmail.com>]

Paul E. McKenney <paulmck <at> linux.vnet.ibm.com> writes:

> The short answer is, as you guessed, because it is not (yet) worth doing.
> This is at least in part because SRCU is not heavily used.
> 
> The philosophy behind the limitation is that the memory overhead of
> the blocks is a small fraction of the memory required to represent
> a thread.  As you say, there are a number of other strategies that can
> be pursued, but the current strategy has the advantage of simplicity.
> In particular, the current strategy does not require a failure return
> from an as-yet-nonexistent call_srcu().  Handling such a failure return
> is certainly possible, but someone would have to show me an extremely
> good reason for putting up with this.  


Yes, I've noticed the extreme simplicity of the current synchronize_srcu().
As for failure return from call_srcu(), I think it's possible to just call
synchronize_srcu() from inside call_srcu() if the latter encounters any errors.
Anyway call_srcu() will be "sometimes blocking" because of the limit on number
of outstanding callbacks, so this must not be a problem.


--
Best regards,
Dmitriy V'jukov