[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 for Xen 4.6 4/4] xl: enabling XL to set per-VCPU parameters of a domain for RTDS scheduler
On Tue, 2015-06-09 at 10:12 -0500, Chong Li wrote: > On Tue, Jun 9, 2015 at 3:01 AM, Dario Faggioli > <dario.faggioli@xxxxxxxxxx> wrote: > How about making > > # xl sched-rtds -d vm1 > > output the per-dom parameters (of vm1), and meanwhile let > > # xl sched-rtds -d vm1 -v all > > output the per-vcpu parameters (of vm1). > > So, in this way, all the "per-vcpu" commands need to consistently specify > "-v". > I see what you mean, but what I don't like is the distinction between per-dom and per-vcpu parameters and command... I don't think it make sense (see below). > > So, IIRC, in patch 3 you are just not touching > > libxl_domain_sched_params_get(), nor sched_rtds_domain_get() and > > (perhaps in another patch) xc_sched_rtds_domain_get(). What I'm asking > > is, what does it mean "users who only do per-dom settings"? What happens > > if I, for instance, do a bunch of: > > > > libxl_vcpu_sched_params_set(...) > > > > for various vcpus, each one with different parameters, and then call: > > > > libxl_domain_sched_params_get(...) > > > > Have you tested this case? What's the output? > > I described this use case in the cover letter. > Ok, yes, now I remember seeing it, and wanting to comment. Then, because of the bad threading of the series, the cover letter is somewhere lost in my xen-devel folder, and I forgot to revisit it when reviewing the single patches. It's certainly my fault, but that's one of the many reasons why the proper threading is important. > "This command should only be used when all vcpus of a domain have the > same parameters, otherwise the output > is pointless. The period and budget shown in the output are equal to > the parameters of the first > VCPU of each domain." > > Or, I think we can just output a warning message in this case. > Neither would be optimal, IMO. If I set the parameters of the vcpus of a VM, then my shift finishes and I leave, how does the sysadmin that does the next shift (or even me, after 1 month) whether I gave to all the vcpus the same parameters, and hence whether the output of `xl sched-rtds -o' (or whatever) can be trusted? What do you mean with "output a warning message"? Do you mean printing a warning if someone tries to retrieve domain scheduling parameters of the RTDS scheduling? Or do you mean print a warning if the vcpus have different parameters? As said, I don't like much this option either, but doing the former may be the only option we have (the latter looks just silly). Dario -- <<This happens because I choose it to happen!>> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) Attachment:
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