RE: [Xen-ia64-devel] Virtual mem map

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Tristan Gingold [mailto:Tristan.Gingold@xxxxxxxx]
>Sent: 2006年1月10日 0:35
>
>[...]
>> > >I think this structure is simple enough to be fast.
>> > >
>> > >For memory usage:
>> > >* Each entry of the first array describes 1GB of memory.  An entry is 32
>> > > bits. 16KB for the first array can describe 2**12 * 2**30 = 2**42 B of
>> > > memory. (Dan's machine physical memory is bellow 2**40).
>> > >* I think 1GB of granule is good enough, unless you have a machine with
>> > > very small DIMM.  In this case, we can use 512MB or 256MB instead of
>> > > 1GB. * 1GB is 2**16 to 2**18 pages.  Thus, the offset may be 18 bits
>> > > and the length 14 bits (to be multiplied by 4).
>> > >As a conclusion, the memory footprint is *very* small, maybe too small ?
>> > >
>> > >memmap related macros must be rewritten.
>> > >
>> > >Tristan.
>Hugh,  I forgot we need also reverse mapping.  I now understand the root of
>virtual mem map!
>
>Tristan.

Yes, exactly.

Thanks,
Kevin

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