Re: Why do we still have 32 bit counters? Interrupt counters overflow within 50 days

[Eric Dumazet]

On Sun, 2014-10-05 at 23:49 +0200, Thomas Gleixner wrote:

> Whats so hard about 64bit counters on 32bit machines?

Not hard, but not trivial either.

> 
> > expensive to handle in particular because these counters are used in
> > performance critical hotpaths.
> 
> The expensive overhead is a single "adcl" instruction.
> 

Assuming a reader do not care of reading garbage yes, while carry is not
yet propagated.



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