| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] Regarding page table management changes from Xen v1to Xe
Ian Pratt wrote:
In another example, mmapped access to a file, the new
approach will incur these two extra faults for every page
fault required to bring a file page to page cache, right?
No, these singleton updates on the Linux demand fault path are issued
with the update_va_mapping hypercall. This is possible because the
virtual address that the pte maps is known, so its possible for Xen to
use a linear pagetable to do the update rather than creating an
on-demand mapping to the domain's pagetable page. This is an important
optimization on 32b where Xen address space is tight.
Just to make sure I understand, we do the linear mapping for performance
(so we don't have to keep remapping) but not necessarily to save VA
space since the linear mapping uses a fixed amount of space.
Is there any reason that we would strictly require a linear mapping
(other than it being convenient)?
Thanks,
Anthony Liguori
Ian
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home