Re: [Xen-devel] [PATCH net] xen-netback: add the scenario which now beyond the range time_after_eq().

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Oct 18, 2013 at 09:40:33AM +0100, David Laight wrote:
> > > My understanding is this patch does not simply double the span, it is
> > > just stricter than the original one. Please check my previous comments,
> > > I paste it here.
> > 
> > No, the code (on a 32-bit arch) just _can't_ handle jiffies differences
> > beyond 2^32, no matter how cleverly you use the respective macros.
> > All arithmetic there is done modulo 2^32.
> 
> I haven't followed this discussion very closely but it might be possible
> to arrange that the 'incorrect lack of credit' only occurs for a few
> seconds every time 'jiffies' wraps - instead of half of the time.
> Then you'd have to be extremely unlucky to hit the timing window.
> 

As I understand it, this is the idea of this patch -- to narrow down the
timing window.

Wei.

>       David
> 
> 
> 
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