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Re: [Xen-devel] DomU's network interface will hung when Dom0 running 32bit

On 2013-10-15 20:58, Wei Liu wrote:
On Tue, Oct 15, 2013 at 07:26:31PM +0800, jianhai luan wrote:
Can you propose a patch?
Because credit_timeout.expire always after jiffies, i judge the
value over the range of time_after_eq() by time_before(now,
vif->credit_timeout.expires). please check the patch.
I don't think this really fix the issue for you. You still have chance
that now wraps around and falls between expires and next_credit. In that
case it's stalled again.
if time_before(now, vif->credit_timeout.expires) is true, time wrap
and do operation. Otherwise time_before(now,
vif->credit_timeout.expires) isn't true, now -
vif->credit_timeout.expires should be letter than ULONG_MAX/2.
Because next_credit large than vif->credit_timeout.expires
(next_crdit = vif->credit_timeout.expires +
msecs_to_jiffies(vif->credit_usec/1000)), the delta between now and
next_credit should be in range of time_after_eq().  So
time_after_eq() do correctly judge.

Not sure I understand you. Consider "now" is placed like this:

    expires   now   next_credit
    ----time increases this direction--->

* time_after_eq(now, next_credit) -> false
* time_before(now, expires) -> false

If now is placed in above environment, the result will be correct (Sending package will be not allowed until next_credit).
* time_after_eq(now, next_credit)  --> false will include two environment:
  expires     now   next_credit
  -----------time increases this direction ---->

  expires      next_credit             next_credit + MAX_LONG/2 now
  -----------time increases this direction ---->

the first environment should be correct to control transmit. the second environment is our included environment.


Then it's stuck again. You're merely narrowing the window, not fixing
the real problem.



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