Re: [Xen-devel] [BUG] XEN-4.8-rc2 sched-rtds does not accept settings
On Tue, 2016-10-18 at 19:52 +0100, Juergen Schinker wrote: > > On Tue, Oct 18, 2016 at 6:51 AM, Wei Liu > > wrote: > > > > > Another thing is that the current RTDS scheduler will only allocate > > the amount of resource to the VCPU you set. Since you set period > > and > > budget to be 2 and 8000, you only get 40% CPU resource. (We > > won't > > get more resource than you set under the current RTDS.) > > > what is the min max? > Not sure what you mean, but I think the answer is that it's a max. I.e., a vcpu will never get more than 8ms every 20ms, which means it will never get more than 40% CPU time. But if it asks less than that, it will (of course!) get less). It can also be seen as a min, but that depends on the system configuration. So far, there is nothing that prevents you to assign 40% of CPU time to 10 vCPUs. This means you've allocated 400% CPUs. If you have, say, only 2 CPUs, you're overbooking, and there's no way everyone will get all of what they ask for. How graceful the performance degradation is, I'll leave it to Meng (I recall EDF does that in a very nice manner, but I can't remember whether that is the case in the actual algorithm RTDS is based on). But again, I'm not sure whether this is what you were asking. > well I just wanted to test it and see how it performs and don't have > a special need for this scheduler > Ah, ok. When doing such experiments, consider using cpupools. They come in very handy, as you can dynamically assign a scheduler to a set of CPUs, move domains there, and test and check whatever you want, without having to reboot with different parameters, etc. > except shutting up loudmouthes who say you can not assure > min resources to a domain :-) > Right, this is a very good purpose... Let us know if you need help on it! :-P Regards, Dario -- <> (Raistlin Majere) - Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) signature.asc Description: This is a digitally signed message part ___ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
Re: [Xen-devel] [BUG] XEN-4.8-rc2 sched-rtds does not accept settings
On Tue, Oct 18, 2016 at 07:52:29PM +0100, Juergen Schinker wrote: > > > - On 18 Oct, 2016, at 17:41, Meng Xu xumengpa...@gmail.com wrote: > > > On Tue, Oct 18, 2016 at 6:51 AM, Wei Liu wrote: > >> CC Dario and Meng > > > > Thank you very much for cc.ing me, Wei! :-) > > > > why are you not on the list? > You only sent to xen-devel@lists.xen.org, which is a public list. Most if not all developers subscribe to that list and have specific filter for it to avoid getting overwhelmed by the traffic. When you CC people directly, maybe they will have another filter to deliver the email to their inbox. Your email will have a better chance to be seen by relevant developers. But keep in mind that when CC'ing people please keep the list of people as relevant as possible. Wei. ___ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
Re: [Xen-devel] [BUG] XEN-4.8-rc2 sched-rtds does not accept settings
- On 18 Oct, 2016, at 17:41, Meng Xu xumengpa...@gmail.com wrote: > On Tue, Oct 18, 2016 at 6:51 AM, Wei Liu wrote: >> CC Dario and Meng > > Thank you very much for cc.ing me, Wei! :-) > why are you not on the list? > The short story is: > If you use "xl sched-rtds -v all", you will see the parameters are changed. > > Another thing is that the current RTDS scheduler will only allocate > the amount of resource to the VCPU you set. Since you set period and > budget to be 2 and 8000, you only get 40% CPU resource. (We won't > get more resource than you set under the current RTDS.) > what is the min max? > We are working on another improved version of the RTDS, which could > let a VCPU get more resource that specified when there is idle > resource left in the system. > If you could tell us what you want to use RTDS to achieve, we could > take that into consideration when we improve the RTDS further. > well I just wanted to test it and see how it performs and don't have a special need for this scheduler except shutting up loudmouthes who say you can not assure min resources to a domain :-) btw i switched to oxenstored Juergen ___ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
Re: [Xen-devel] [BUG] XEN-4.8-rc2 sched-rtds does not accept settings
On Tue, Oct 18, 2016 at 6:51 AM, Wei Liu wrote: > CC Dario and Meng Thank you very much for cc.ing me, Wei! :-) > > On Mon, Oct 17, 2016 at 10:55:21PM +0100, Juergen Schinker wrote: >> Hey Meng XU Hi, Thanks for your interest in RTDS scheduler! :-) >> >> >> xl -vf sched-rtds -v all -d 0 -p 2 -b 8000 >> >> whatever I set - the changes are not accepted and stay like you see further >> down >> >> and the system feels very lame >> >> Cpupool Pool-0: sched=RTDS >> NameIDPeriodBudget >> Domain-0 0 1 4000 >> zimbra 1 1 4000 >> ethereum-os 2 1 4000 >> mirot3 1 4000 >> wily 4 1 4000 I guess you used xl sched-rtds to show the paramters. The "xl sched-rtds" is a legacy command. It is supposed to show the period and budget of *all* VCPUs of the same domain. In Xen 4.5, RTDS scheduler only allows setting same period and budget for *all* VCPUs of the same domain. In Xen 4.7, RTDS scheduler allows setting individual period and budget for each VCPU of the same domain. Then "xl sched-rtds" won't make sense because VCPUs have different periods and budgets. The short story is: If you use "xl sched-rtds -v all", you will see the parameters are changed. Another thing is that the current RTDS scheduler will only allocate the amount of resource to the VCPU you set. Since you set period and budget to be 2 and 8000, you only get 40% CPU resource. (We won't get more resource than you set under the current RTDS.) We are working on another improved version of the RTDS, which could let a VCPU get more resource that specified when there is idle resource left in the system. If you could tell us what you want to use RTDS to achieve, we could take that into consideration when we improve the RTDS further. Thanks, Meng --- Meng Xu PhD Student in Computer and Information Science University of Pennsylvania http://www.cis.upenn.edu/~mengxu/ ___ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
Re: [Xen-devel] [BUG] XEN-4.8-rc2 sched-rtds does not accept settings
On Tue, 2016-10-18 at 11:51 +0100, Wei Liu wrote: > CC Dario and Meng > Hi, Thanks Wei for the Cc... > On Mon, Oct 17, 2016 at 10:55:21PM +0100, Juergen Schinker wrote: > > > > xl -vf sched-rtds -v all -d 0 -p 2 -b 8000 > > > > whatever I set - the changes are not accepted and stay like you see > > further down > > > > and the system feels very lame > > > > Cpupool Pool-0: sched=RTDS > > NameIDPeriodBudget > > Domain-0 0 1 4000 > > zimbra 1 1 4000 > > ethereum-os 2 1 4000 > > mirot3 1 4000 > > wily 4 1 4000 > > Right, but what does the following shows: xl sched-rtds -d 0 -v all ? On my system, just using `xl sched-rtds` as above also still shows the 4000/1 budget over period pairs, but adding '-v all' shows the correct (i.e., the new) parameters. In fact, the two commands are basically showing different things. I agree it's not really clear, and I'll think to ways of improving the situation (e.g., by improving the documentation, but also by making the `xl' interface more consistent). About the 'system feels lame', what does that exactly mean? Actually, what is it that you are trying to achieve by using RTDS? RTDS is a special purpose scheduler, and should be chosen for the proper reasons and configured accurately. Typical use case is need for deterministic/real-time scheduling of VMs. Oh, and also, default parameters are 4000/1=40% utilization. By setting them to 8000/2=40%, you're not changing much, at least nothing that will be noticeable as a 'general system feeling', because all domains (well, each vCPU of each domain), including dom0 (dom0's vCPUs), are still limited to use at most 40% of pCPU time --although with different periodicity. Regards, Dario -- <> (Raistlin Majere) - Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) signature.asc Description: This is a digitally signed message part ___ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
Re: [Xen-devel] [BUG] XEN-4.8-rc2 sched-rtds does not accept settings
CC Dario and Meng On Mon, Oct 17, 2016 at 10:55:21PM +0100, Juergen Schinker wrote: > Hey Meng XU > > > xl -vf sched-rtds -v all -d 0 -p 2 -b 8000 > > whatever I set - the changes are not accepted and stay like you see further > down > > and the system feels very lame > > Cpupool Pool-0: sched=RTDS > NameIDPeriodBudget > Domain-0 0 1 4000 > zimbra 1 1 4000 > ethereum-os 2 1 4000 > mirot3 1 4000 > wily 4 1 4000 > > host : xen > release: 4.7.0-1-amd64 > version: #1 SMP Debian 4.7.6-1 (2016-10-07) > machine: x86_64 > nr_cpus: 4 > max_cpu_id : 3 > nr_nodes : 1 > cores_per_socket : 2 > threads_per_core : 2 > cpu_mhz: 2312 > hw_caps: > b7ebfbff:77bae3ff:28100800:0001:0001:0281::0100 > virt_caps : hvm hvm_directio > total_memory : 32711 > free_memory: 0 > sharing_freed_memory : 0 > sharing_used_memory: 0 > outstanding_claims : 0 > free_cpus : 0 > xen_major : 4 > xen_minor : 8 > xen_extra : .0-rc > xen_version: 4.8.0-rc > xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 > hvm-3.0-x86_32p hvm-3.0-x86_64 > xen_scheduler : rtds > xen_pagesize : 4096 > platform_params: virt_start=0x8000 > xen_changeset : Mon Oct 10 11:10:56 2016 -0700 git:68dc718 > xen_commandline: placeholder sched=rtds iommu=1 > cc_compiler: gcc (Debian 6.2.0-6) 6.2.0 20161010 > cc_compile_by : root > cc_compile_domain : > cc_compile_date: Sun Oct 16 23:56:56 BST 2016 > build_id : 847a9dd70ab5f581818fa9cc09ed609ce2b420d1 > xend_config_format : 4 > > ___ > Xen-devel mailing list > Xen-devel@lists.xen.org > https://lists.xen.org/xen-devel ___ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
