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Re: [Xen-devel] Pending Disk io requests during live migration

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Pending Disk io requests during live migration
From: Kaushik Bhandankar <kaushikb@xxxxxxxxxxxxx>
Date: Thu, 04 Oct 2007 01:22:00 -0400
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one modification:

register_savevm() in tools/ioemu/vl.c is simply used to register the save & load routines......... register_savevm() is called in tools/ioemu/hw/ide.c:pci_piix_ide_init to register pci_ide_save() and pci_ide_load() as the save & load routines for IDE disks.......

But I am still unsure as to where these save/load routines for IDE disks get invoked....

Kaushik Bhandankar wrote:
Hello

I am trying to implement functionality in fully-virtualized xen wherein the responses to the pending disk I/O requests during live VM migration get trasnsferred to the new VMM form the old VMM. Specifically, I am looking at IDE disk (tools/ioemu/hw/ide.c)

Basically, ide.c:pci_ide_save() saves the state of the IDE disk in a QEMUFile and this file is sent over the network (can somebody point me to the code where this happens ??)) so that the new VMM (where the VM has migrated) invokes ide.c:pci_ide_load() to retrieve the IDE Disk contents form the file. As of now, the pending disk I/O requests do not get saved in this file so these pending disk I/O requests are not available when executing pci_ide_load().

I am still trying to figure out where the pending Disk I/O requests get stored in the VMM so that during live VM migration, these requests can be put in the QEMUFile (As mentioned above)

Also, looks like tools/ioemu/vl.c:register_savevm() seems to be invoking pci_ide_save()/pci_ide_load() methods but I am still looking for all possible scenarios in which pci_ide_save()/pci_ide_load() gets invoked.

Any help in locating the code would be greatly appreciated.

-Kaushik

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