[Linux-cachefs] Data Redundancy

[gaurav]

hello every1

sorry but i wanted to know exactly two points :
1) Is default page cache(means not useing MMAP_SHARED()) is shareable among
different user level process .

2)Is default page cache(means not useing MMAP_SHARED()) is shareable among
diffrent protection domain(means kernel and user adrress space)
thank you


On 11/20/06, David Howells <dhowells at redhat.com> wrote:
>
> gaurav <gaurav1207 at gmail.com> wrote:
>
> >   i wanted to know that in linux 2.6 kernel is the data copying still
> > there.. in detail whenever any file is accessed from the disk by any
> > application program via kernel the file is copied into the kernel
> cache.. i
> > wanted to know that whether another copy of that data is copied in the
> user
> > space also or not???
>
> I'm not sure what you're asking exactly, but CacheFiles still copies data
> between pages belonging to, say, NFS and pages belonging to, say, Ext3
> when
> the data is read from the server (cold cache), and then copies them back
> again
> when there's a warm cache available.
>
> I'd like to use direct I/O, but the current direct I/O internal interface
> really isn't set up to do this: it assumes a userspace address to copy
> to/from.
>
> David
>
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-- 
Gaurav....