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

On 2013-10-18 19:24, Wei Liu wrote:
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.
Jan,  do you agree the idea or have better suggestion to me.




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