From mboxrd@z Thu Jan 1 00:00:00 1970 From: annie li Subject: Re: [Xen-devel] DomU's network interface will hung when Dom0 running 32bit Date: Wed, 16 Oct 2013 17:39:43 +0800 Message-ID: <525E5EDF.4030904@oracle.com> References: <52590DFE.6080203@oracle.com> <20131014111958.GE11739@zion.uk.xensource.com> <525CAC21.5040202@oracle.com> <1381826609.24708.135.camel@kazak.uk.xensource.com> <525D0C41.2080407@oracle.com> <20131015100624.GB29436@zion.uk.xensource.com> <525D2667.6040102@oracle.com> <20131015125802.GR11739@zion.uk.xensource.com> <525E41CF.7090008@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Wei Liu , xen-devel@lists.xenproject.org, Ian Campbell , netdev@vger.kernel.org To: jianhai luan Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:42774 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760301Ab3JPJjx (ORCPT ); Wed, 16 Oct 2013 05:39:53 -0400 In-Reply-To: <525E41CF.7090008@oracle.com> Sender: netdev-owner@vger.kernel.org List-ID: 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