From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: Xen 4.5 random freeze question Date: Wed, 19 Nov 2014 13:26:32 +0000 Message-ID: <546C9A88.6000100@linaro.org> References: <1416399227.29243.33.camel@citrix.com> <546C8BD9.8090406@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrii Tseglytskyi Cc: "xen-devel@lists.xen.org" , Ian Campbell , Stefano Stabellini List-Id: xen-devel@lists.xenproject.org On 11/19/2014 12:40 PM, Andrii Tseglytskyi wrote: > Hi Julien, > > On Wed, Nov 19, 2014 at 2:23 PM, Julien Grall wrote: >> On 11/19/2014 12:17 PM, Stefano Stabellini wrote: >>> On Wed, 19 Nov 2014, Ian Campbell wrote: >>>> On Wed, 2014-11-19 at 11:42 +0000, Stefano Stabellini wrote: >>>>> So it looks like there is not actually anything wrong, is just that you >>>>> have too much inflight irqs? It should cause problems because in that >>>>> case GICH_HCR_UIE should be set and you should get a maintenance >>>>> interrupt when LRs become available (actually when "none, or only one, >>>>> of the List register entries is marked as a valid interrupt"). >>>>> >>>>> Maybe GICH_HCR_UIE is the one that doesn't work properly. >>>> >>>> How much testing did this aspect get when the no-maint-irq series >>>> originally went in? Did you manage to find a workload which filled all >>>> the LRs or try artificially limiting the number of LRs somehow in order >>>> to provoke it? >>>> >>>> I ask because my intuition is that this won't happen very much, meaning >>>> those code paths may not be as well tested... >>> >>> I did test it by artificially limiting the number of LRs to 1. >>> However there have been many iterations of that series and I didn't run >>> this test at every iteration. >> >> am I the only to think this may not be related to this bug? All the LRs >> are full with IRQ of the same priority. So it's valid. >> >> As gic_restore_pending_irqs is called every time that we return to the >> guest. It could be anything else. >> >> It would be interesting to see why we are trapping all the time in Xen. >> > > I may perform any test if you have some specific scenario. I have no specific scenario in my mind :/. It looks like I'm able to reproduce it on my ARM board by the restricted the number of LRs to 1. I will investigate. Regards, -- Julien Grall