RE: [Xen-devel] [PATCH 4/4] Enable VirtualPC 2007 run on top of XEN: add_write_for_data_pages

["Su, Disheng" <disheng.su@xxxxxxxxx>]

Tim Deegan wrote:
> Hi,
> 
> At 14:24 +0800 on 01 Feb (1201875871), Su, Disheng wrote:
>> There are two cases for CR0.wp emulation: one is for page table write
>> emulation, another is for data page write emulation. We found more
>> than 100,000 page faults per second for the later case. This case
>> can be optimized by setting _PAGE_RW bit for this ReadOnly data page
>> when guest CR0.wp is 0, and remove it when CR0.wp is 1. With this
>> patch, page faults is reduced to about 10,000 at average.
> 
> Unfortunately, this isn't safe for SMP guests -- vcpu0's wp bit being
> clear shouldn't let vcpu1 ignore the _PAGE_RW bits on shared mappings.
>  
Yes, this situation havn't be handled. Could you give me some
suggestion?
How about out-of-sync shadow for CR0.wp = 0?
> Sheers,
> 
> Tim.



Best Regards,
Disheng, Su

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel