[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore: zero ioreq page only one time
> -----Original Message----- > From: Wen Congyang [mailto:wency@xxxxxxxxxxxxxx] > Sent: 12 June 2015 12:10 > To: Paul Durrant; Yang Hongyang; Andrew Cooper; xen-devel@xxxxxxxxxxxxx > Cc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx; > yunhong.jiang@xxxxxxxxx; Eddie Dong; rshriram@xxxxxxxxx; Ian Jackson > Subject: Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore: zero ioreq > page only one time > > On 06/12/2015 06:54 PM, Paul Durrant wrote: > >> -----Original Message----- > >> From: Wen Congyang [mailto:wency@xxxxxxxxxxxxxx] > >> Sent: 12 June 2015 11:26 > >> To: Paul Durrant; Yang Hongyang; Andrew Cooper; xen- > devel@xxxxxxxxxxxxx > >> Cc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx; > >> yunhong.jiang@xxxxxxxxx; Eddie Dong; rshriram@xxxxxxxxx; Ian Jackson > >> Subject: Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore: zero > ioreq > >> page only one time > >> > >> On 06/12/2015 03:41 PM, Paul Durrant wrote: > >>>> -----Original Message----- > >>>> From: Wen Congyang [mailto:wency@xxxxxxxxxxxxxx] > >>>> Sent: 12 June 2015 04:22 > >>>> To: Paul Durrant; Yang Hongyang; Andrew Cooper; xen- > >> devel@xxxxxxxxxxxxx > >>>> Cc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx; > >>>> yunhong.jiang@xxxxxxxxx; Eddie Dong; rshriram@xxxxxxxxx; Ian Jackson > >>>> Subject: Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore: zero > >> ioreq > >>>> page only one time > >>>> > >>>> On 06/11/2015 09:25 PM, Paul Durrant wrote: > >>>>>> -----Original Message----- > >>>>>> From: Yang Hongyang [mailto:yanghy@xxxxxxxxxxxxxx] > >>>>>> Sent: 11 June 2015 13:59 > >>>>>> To: Paul Durrant; Wen Congyang; Andrew Cooper; xen- > >>>> devel@xxxxxxxxxxxxx > >>>>>> Cc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx; > >>>>>> yunhong.jiang@xxxxxxxxx; Eddie Dong; rshriram@xxxxxxxxx; Ian > Jackson > >>>>>> Subject: Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore: > zero > >>>> ioreq > >>>>>> page only one time > >>>>>> > >>>>>> > >>>>>> > >>>>>> On 06/11/2015 06:20 PM, Paul Durrant wrote: > >>>>>>>> -----Original Message----- > >>>>>>>> From: Wen Congyang [mailto:wency@xxxxxxxxxxxxxx] > >>>>>>>> Sent: 11 June 2015 09:48 > >>>>>>>> To: Paul Durrant; Andrew Cooper; Yang Hongyang; xen- > >>>>>> devel@xxxxxxxxxxxxx > >>>>>>>> Cc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx; > >>>>>> [...] > >>>>>>> > >>>>>>>> > >>>>>>>> In our implementation, we don't start a new emulator. The codes > >> can > >>>>>> work, > >>>>>>>> but some bugs may be not triggered. > >>>>>>>> > >>>>>>> > >>>>>>> How do you reconcile the incoming QEMU save record with the > >> running > >>>>>> emulator state? > >>>>>> > >>>>>> We introduce a qmp command "xen-load-devices- > >>>>>> state"(libxl__qmp_restore) which > >>>>>> can restore the emulator state. The step of resotre emulator state at > a > >>>>>> checkpoint is: > >>>>>> > >>>>>> 1. libxl__qmp_stop -> vm_stop() in qemu > >>>>>> 2. libxl__qmp_restore -> load_vmstate() in qemu > >>>>>> 3. libxl__qmp_resume -> vm_start() in qemu > >>>>>> > >>>>> > >>>>> Ok, that sounds like the ideal time to hook back into Xen by creating a > >> new > >>>> ioreq server. > >>>> > >>>> I have some questions about ioreq server: > >>>> 1. If we use old version xen and newest version qemu, is it OK? Is > default > >>>> ioreq server created when the guest is created. > >> xen_create_ioreq_server() > >>>> does > >>>> nothing, and xen_get_ioreq_server_info() will get the default ioreq > >> server > >>>> information. > >>>> Is it right? > >>> > >>> No. It's not compatible in that direction. A new Xen will work with an old > >> QEMU but not the other way round. > > If the xen is newest, and qemu is old, how is the default ioreq server created > for the emulator? Will the old qemu call xc_get_hvm_param(), and the > hypervisor > then creates a default ioreq server? > get is a 'readonly' operation, and creating the default ioreq server in it is > very strange. > Might be strange, but that's the way it's done. > >>> > >>>> 2. Why we create a default ioreq server when getting the hvm param if > >> there > >>>> is already a > >>>> not default ioreq server? > >>> > >>> If something reads the 'legacy' HVM params then that is Xen's trigger to > >> create the default server. Any 'new' emulator should be using the ioreq > >> server hypercalls so the default server will not be needed. > >> > >> If there are two ioreq servers: default ioreq server, and a ioreq server > >> created by emulator. The guest can work it correctly in > >> this case? > > > > You mean a secondary emulator? Yes, that's why there is the notion of > default ioreq server... to allow a secondary emulator to be used even when > an old QEMU is in use. > > No, only one emulator. Can we run more than one emulator for one hvm > guest? How > to do it? > Yes, more than one emulator can run. There's nothing in libxl to do it, but we do it in XenServer using XAPI. > > > >> Is there any application(not emulator) that uses the libxenctrl > >> directly? > >> > > > > What do you mean by application? Toolstacks may use libxenctrl. > > For example: libvirt. I know it uses libxl now. Is there any similar > application > which uses libxenctrl. Well, XAPI uses it for one. Paul > > Thanks > Wen Congyang > > > > > Paul > > > >> Thanks > >> Wen Congyang > >> > >>> > >>>> 3. In the far end, we will clear the ioreq page, and this ioreq page is > used > >> for > >>>> default > >>>> ioreq server, is it right? > >>> > >>> Yes, AFAIK it's only the 'magic' pages that get cleared at the far end - > >>> and > >> that includes the default server pages. Other ioreq servers will have their > >> pages cleared on re-insertion to the P2M at the source end when the > server > >> is disabled. > >>> > >>> Paul > >>> > >>>> > >>>> Thanks > >>>> Wen Congyang > >>>> > >>>>> > >>>>> Paul > >>>>> > >>>>>>> > >>>>>>> Paul > >>>>>>> > >>>>>>>> Thanks > >>>>>>>> Wen Congyang > >>>>>>>> > >>>>>>>>> > >>>>>>>>> Paul > >>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> Thanks > >>>>>>>>>> Wen Congyang > >>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>>> Paul > >>>>>>>>>>> > >>>>>>>>>>>> We will set to the guest to a new state, the old state should > be > >>>>>>>> dropped. > >>>>>>>>>>>> > >>>>>>>>>>>> Thanks > >>>>>>>>>>>> Wen Congyang > >>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>>>> Paul > >>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> Thanks > >>>>>>>>>>>>>> Wen Congyang > >>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Paul > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> Thanks > >>>>>>>>>>>>>>>> Wen Congyang > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>> ~Andrew > >>>>>>>>>>>>>>>>> . > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> . > >>>>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>>>>> . > >>>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> > _______________________________________________ > >>>>>>>>>>>> Xen-devel mailing list > >>>>>>>>>>>> Xen-devel@xxxxxxxxxxxxx > >>>>>>>>>>>> http://lists.xen.org/xen-devel > >>>>>>>>>>> > >>>>>>>>>>> _______________________________________________ > >>>>>>>>>>> Xen-devel mailing list > >>>>>>>>>>> Xen-devel@xxxxxxxxxxxxx > >>>>>>>>>>> http://lists.xen.org/xen-devel > >>>>>>>>>>> . > >>>>>>>>>>> > >>>>>>>>> > >>>>>>>>> . > >>>>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> _______________________________________________ > >>>>>>> Xen-devel mailing list > >>>>>>> Xen-devel@xxxxxxxxxxxxx > >>>>>>> http://lists.xen.org/xen-devel > >>>>>>> . > >>>>>>> > >>>>>> > >>>>>> -- > >>>>>> Thanks, > >>>>>> Yang. > >>>>> . > >>>>> > >>> > >>> . > >>> > > > > . > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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