RE: [Xen-devel] [PATCH] TSC scaling for live migration between platforms with different TSC frequecies

["Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>]

Tim Deegan wrote:
> At 03:56 +0100 on 18 Jun (1245297406), Zhang, Xiantao wrote:
>> --- a/xen/include/public/arch-x86/hvm/save.h Fri Feb 20 17:02:36
>> 2009 +0000 +++ b/xen/include/public/arch-x86/hvm/save.h      Tue Jun 16
>> 22:41:06 2009 -0400 @@ -38,7 +38,7 @@ struct hvm_save_header {
>>      uint32_t version;           /* File format version */
>>      uint64_t changeset;         /* Version of Xen that saved this
>>      file */ uint32_t cpuid;             /* CPUID[0x01][%eax] on the
>> saving machine */ -    uint32_t pad0; +    uint32_t gtsc_khz;       
>> /* Guest's TSC frequency in kHz */  }; 
>> 
>>  DECLARE_HVM_SAVE_TYPE(HEADER, 1, struct hvm_save_header);
> 
> I'm not sure this is the best place for this field -- it's a property
> of the guest CPU rather than of the host that saved the record.  I
> think it would be better to give it its own save record type. 
Hi, Tim
    Guest's preferred TSC frequency should be per-domain concept instead of 
constraining it to vcpus.  If we introduce a separate save type for this only 
field,  maybe too heavy.
In addition, TSC frequency field is saved by original proposal about image 
format, but don't know why it is dropped.  See attached pdf doc. 
Xiantao

Attachment: pdfghoqtwxKby.pdf
Description: pdfghoqtwxKby.pdf

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