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Date: Wed, 16 Oct 2013 21:08:03 +0800 From: jianhai luan <jianhai.luan@...cle.com> To: annie li <annie.li@...cle.com> CC: Wei Liu <wei.liu2@...rix.com>, xen-devel@...ts.xenproject.org, Ian Campbell <Ian.Campbell@...rix.com>, netdev@...r.kernel.org Subject: Re: [Xen-devel] DomU's network interface will hung when Dom0 running 32bit On 2013-10-16 17:39, annie li wrote: > > 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's express, my option is consistent with Annie. Jason > > Thanks > Annie >>> >>> Wei. >>> >>>> Jason >>>>> Wei. >> Jason. >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@...ts.xen.org >> http://lists.xen.org/xen-devel > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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