lkml.org 
[lkml]   [2009]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Copy-on-write

> If the source and destination pages are not in high memory (exactly
> where this boundary is depends on your architecture) they do not need
> to be mapped before copying. See cow_user_page in mm/memory.c,
> copy_user_highpage in include/linux/highmem.h and kmap_atomic in
> arch/x86/mm/highmem_32.c (as well as implementations for other
> architectures)

> Note that on 64-bit platforms, generally there will be no high memory,
> and so remappings will never be needed to carry out a COW.

Thanks for the quick reply. In general if the kernel wishes to read any
arbitrary page mapped to an application's address space, will the kernel
cause a page fault on that page, since the page is currently not in its
address space and the kernel is wishing to read from this page?

Thanks

--
View this message in context: http://www.nabble.com/Copy-on-write-tp22736146p22736728.html
Sent from the linux-kernel mailing list archive at Nabble.com.



\
 
 \ /
  Last update: 2009-03-27 07:47    [W:0.047 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site