Basic HighMeM Question

[piyush moghe]

Thanks Mulyadi and Prabhu for your enlightening description.

What a plight!!! memory has become soo cheap nowadays that I don't have less
than 1GB system and difficult to find someone in my knowledge having less
than 1 GB memory.

Although does this means that pages in FCOM will never have page fault? and
if this is true is this the reason why we assign NULL to memory descriptor (
mm_struct ) for kernel threads?


Regards,
Piyush

On Tue, Jun 28, 2011 at 8:56 PM, Mulyadi Santosa
<mulyadi.santosa at gmail.com>wrote:

> Hi :)
>
> On Tue, Jun 28, 2011 at 17:49, Prabhu nath <gprabhunath at gmail.com> wrote:
> > Dear Mulyadi,
> >
> > You are always an important character to jump in to any discussion and it
> > will be our great pleasure.
>
> Thanks :) Well, sometimes I just feel hesitate to break into someone's
> else discussion.
>
> > Please see inline for my views.
> >
> > On Tue, Jun 28, 2011 at 3:46 PM, Mulyadi Santosa <
> mulyadi.santosa at gmail.com>
> > wrote:
> >     In a 3G/1G partition. 1G of Kernel virtual address space is divided
> into
> > 896MB and 128 MB regions. I name them as
> >   Fixed Constant Offset mapped region (FCOM) - 0xC0000000 to 0xF8000000
> >   Dynamically Arbitrarily Mappable region (DAMR) - 0xF8000000 to
> 0xFFFFFFFF
>
> Great naming! You beat me on that aspect :)
>
> PS: Once there was a patch to create 4:4 VM split written by Ingo
> Molnar. It does maximize address space at the expense of full TLB
> flush on every context switch. AFAIK it once included in Fedora core 2
> or 3, but dropped afterward since it puts more negative impacts rather
> than positive enhancement (in virtual memory management point of view)
>
> --
> regards,
>
> Mulyadi Santosa
> Freelance Linux trainer and consultant
>
> blog: the-hydra.blogspot.com
> training: mulyaditraining.blogspot.com
>
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