On Tue, Mar 15, 2016 at 10:14 PM, Meng Xu <men...@cis.upenn.edu> wrote: > On Tue, Mar 15, 2016 at 1:22 PM, Chong Li <lichong...@gmail.com> wrote: >> On Tue, Mar 15, 2016 at 11:41 AM, Dario Faggioli >> <dario.faggi...@citrix.com> wrote: >>> On Tue, 2016-03-15 at 11:22 -0500, Chong Li wrote: >>>> On Mon, Mar 14, 2016 at 5:05 AM, Dario Faggioli >>>> <dario.faggi...@citrix.com> wrote: >>>> > >>> >>> We said 'once' and then 'once per domain', but something I'd be fine >>> with (coupled with keeping G_WARNING) would be 'once per operation'. >>> Basically, if a domain has 128 vcpus, and an hypercall tries to set all >>> of them to period=100, budget=50, we just print the warning once. Then, >>> if after a while the sysadmin tries the same again, we again just log >>> once, etc. >>> >>> Doing this seems much easier, as the 'warned' flag could just be a >>> local variable of the hypercall implementation. I'm quite sure that >>> would work if there is not any continuation/re-issueing mechanism in >>> the hypercall in question. BUT in our case there is, so things may be >>> more complicated... :-/ >>> >>> Had you thought about a solution like this already? If no, can you see >>> whether there is a nice and easy way to make something like what I just >>> described above to work in our case? >>> >> How about: >> >> We create a global variable in sched_rt.c: >> /* This variable holds its value through hyerpcall re-issueing. >> * When finding vcpu settings with too low budget or period (e.g, >> 100 us), we print a warning >> * and set this variable "true". No more warnings are printed >> until this variable >> * becomes false. >> */ >> static bool warned; >> Initialize it as "false" in rt_init(). >> In your example, >> we "warned = true" when we find the first vcpu has budget less than >> 100 us. Outside >> of the while loop, we do: >> if ( index == op->u.v.nr_vcpus ) /* no more hypercall re-issueing */ >> warned = false; >> > Hi Chong, > > I don't think creating a global variable just for the warning thing is > a better idea. Even if we do want such a variable, it should only > occur in rt_dom_cntl() function, since it is only used in > rt_dom_cntl(). > Global variable should be used "globally", isn't it. ;-) > You're right.
If we define static bool warned; at the beginning of rt_dom_cntl(), do we need to initialize it? If without initialization, I think its default value is "false", which is just what we need. Chong -- Chong Li Department of Computer Science and Engineering Washington University in St.louis _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
