[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
At 2015/6/12 23:31, Paul Durrant Wrote: -----Original Message----- From: Wen Congyang [mailto:ghostwcy@xxxxxxxxx] Sent: 12 June 2015 16:05 To: Paul Durrant; Wen Congyang; 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 At 2015/6/12 19:48, Paul Durrant Wrote:-----Original Message----- From: Wen Congyang [mailto:wency@xxxxxxxxxxxxxx] Sent: 12 June 2015 12:10 To: Paul Durrant; Yang Hongyang; Andrew Cooper; xen-devel@xxxxxxxxxxxxxCc: 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: zeroioreqpage 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@xxxxxxxxxxxxxCc: 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: zeroioreqpage 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@xxxxxxxxxxxxxCc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx; yunhong.jiang@xxxxxxxxx; Eddie Dong; rshriram@xxxxxxxxx; IanJacksonSubject: Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore:zeroioreqpage 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@xxxxxxxxxxxxxCc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx; yunhong.jiang@xxxxxxxxx; Eddie Dong; rshriram@xxxxxxxxx; IanJacksonSubject: Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore:zeroioreqpage 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@xxxxxxxxxxxxxCc: Wei Liu; Ian Campbell; guijianfeng@xxxxxxxxxxxxxx;[...]In our implementation, we don't start a new emulator. Thecodescanwork,but some bugs may be not triggered.How do you reconcile the incoming QEMU save record with therunningemulator state? We introduce a qmp command "xen-load-devices- state"(libxl__qmp_restore) which can restore the emulator state. The step of resotre emulator stateatacheckpoint is: 1. libxl__qmp_stop -> vm_stop() in qemu 2. libxl__qmp_restore -> load_vmstate() in qemu 3. libxl__qmp_resume -> vm_start() in qemuOk, that sounds like the ideal time to hook back into Xen bycreating anewioreq server. I have some questions about ioreq server: 1. If we use old version xen and newest version qemu, is it OK? Isdefaultioreq server created when the guest is created.xen_create_ioreq_server()does nothing, and xen_get_ioreq_server_info() will get the defaultioreqserverinformation. Is it right?No. It's not compatible in that direction. A new Xen will work with anoldQEMU but not the other way round.If the xen is newest, and qemu is old, how is the default ioreq servercreatedfor 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.If I only want to get the default ioreq server pfn, and don't want to create the default ioreq server, how can I do it?At the moment you can't. If you read the pfns then you will instantiate the server, which I agree is a bit of a problem if you're only doing a domain save. Yes, but we have to instantiate the server so old version qemu can work.Can we add a new interface to just get the ioreq pfn, buffer ioreq pfn/evtchn? For example HVM_PARAM_DEFAULT_IOREQ_PFN. Thanks Wen congyang PaulThanks Wen Congyang2. Why we create a default ioreq server when getting the hvmparam ifthereis already a not default ioreq server?If something reads the 'legacy' HVM params then that is Xen's triggertocreate 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 ofdefault ioreq server... to allow a secondary emulator to be used evenwhenan 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, butwe 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 similarapplicationwhich uses libxenctrl.Well, XAPI uses it for one. PaulThanks Wen CongyangPaulThanks Wen Congyang3. In the far end, we will clear the ioreq page, and this ioreq page isusedfordefault ioreq server, is it right?Yes, AFAIK it's only the 'magic' pages that get cleared at the far end -andthat includes the default server pages. Other ioreq servers will havetheirpages cleared on re-insertion to the P2M at the source end when theserveris disabled.PaulThanks Wen CongyangPaulPaulThanks Wen CongyangPaulThanks Wen CongyangPaulWe will set to the guest to a new state, the old stateshouldbedropped.Thanks Wen CongyangPaulThanks Wen CongyangPaulThanks 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 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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