Re: Summary of resource management discussion

[Paul Jackson]

Herbert wrote:
> looks good to me, except for the potential issue with
> the double indirection introducing too much overhear

It's not the indirection count that I worry about.

It's the scalability of the locking.  We must avoid as
much as possible adding any global locks on key code paths.
This means:
 1) be reluctant to add them to fork/exit
 2) just RCU locks on per-job (or finer grain) data when on
	the normal page allocation path
 3) nothing outside the current task context for the normal
	task scheduling code path.

A global lock on the wrong code path is fatal for scaling
big NUMA boxes.

... now whether or not that is an issue here, I don't claim
to know.   I'm just worried that it could be.

Atomic data, such as global counters, is just as bad.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@xxxxxxx> 1.925.600.0401
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