From: annie li <annie.li@oracle•com>
To: jianhai luan <jianhai.luan@oracle•com>
Cc: Wei Liu <wei.liu2@citrix•com>,
xen-devel@lists•xenproject.org,
Ian Campbell <Ian.Campbell@citrix•com>,
netdev@vger•kernel.org
Subject: Re: [Xen-devel] DomU's network interface will hung when Dom0 running 32bit
Date: Wed, 16 Oct 2013 17:39:43 +0800 [thread overview]
Message-ID: <525E5EDF.4030904@oracle.com> (raw)
In-Reply-To: <525E41CF.7090008@oracle.com>
On 2013-10-16 15:35, jianhai luan wrote:
>
> 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
>>
>> Then it's stuck again. You're merely narrowing the window, not fixing
>> the real problem.
>
> The above environment isn't stack again. The netback will pending one
> timer to process the environment.
>
> The attachment program will prove if !(time_after_eq(now, next_credit)
> || time_before(now, vif->credit_timeout.expires)), now will only be
> placed in above environment [ expires next_credit), and the above
> environment will be processed by timer in soon.
Or check following to see what the if condition really do,
----------expires-------now-------credit---------- is the only case
where we need to add a timer.
Other cases like following would match the if condition above, then no
timer is added.
----------expires----------credit------now------
-----now-----expires----------credit----------
Or we can consider the extreme condition, when the rate control does not
exist, "credit_usec" is zero, and "next_credit" is equal to "expires".
The above if condition would cover all conditions, and no rate control
really happens. If credit_usec is not zero, the "if condition" would
cover the range outside of that from expires to next_credit.
Even if "now" is wrapped again into the range from "expires" to
"next_credit", the "next_credit" that is set in __mod_timer is
reasonable value(this can be gotten from credit_usec), and the timer
would be hit soon.
Thanks
Annie
>>
>> Wei.
>>
>>> Jason
>>>> Wei.
> Jason.
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists•xen.org
> http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2013-10-16 9:39 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-12 8:53 DomU's network interface will hung when Dom0 running 32bit jianhai luan
2013-10-14 11:19 ` Wei Liu
2013-10-15 2:44 ` jianhai luan
2013-10-15 8:43 ` Ian Campbell
2013-10-15 9:34 ` jianhai luan
2013-10-15 10:06 ` Wei Liu
2013-10-15 11:26 ` jianhai luan
2013-10-15 12:58 ` Wei Liu
2013-10-15 14:29 ` jianhai luan
2013-10-15 14:49 ` Wei Liu
2013-10-15 14:50 ` Ian Campbell
2013-10-15 15:19 ` jianhai luan
2013-10-15 16:03 ` Wei Liu
2013-10-15 16:23 ` jianhai luan
2013-10-16 0:15 ` jianhai luan
2013-10-16 7:35 ` jianhai luan
2013-10-16 9:39 ` annie li [this message]
2013-10-16 13:08 ` [Xen-devel] " jianhai luan
2013-10-16 13:47 ` Wei Liu
2013-10-16 15:04 ` jianhai luan
2013-10-16 15:17 ` Wei Liu
2013-10-16 16:11 ` David Vrabel
2013-10-16 16:44 ` jianhai luan
2013-10-16 15:26 ` annie li
2013-10-16 7:10 ` annie li
2013-10-16 8:46 ` Ian Campbell
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