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Subject: Re: Tell me about Alpha

Author: Robert Hyatt

Date: 16:03:14 07/08/99

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On July 08, 1999 at 15:02:04, Eugene Nalimov wrote:

>On July 08, 1999 at 10:48:26, Robert Hyatt wrote:
>
>>On July 08, 1999 at 07:41:27, David Blackman wrote:
>>
>>>On July 07, 1999 at 13:01:42, Bruce Moreland wrote:
>>>
>>>>
>>>>On July 07, 1999 at 08:02:14, Rajen Gupta wrote:
>>>>
>>>>>when microsoft the great releases a 64 bit version of win9x/NT, would that be
>>>>>the time when the alpha processor comes into its own?
>>>>
>>>>I don't see why, but, warning, I am not an expert on the Alpha.
>>>>
>>>>The compiler you get from Microsoft, which I am told has a Digital back end,
>>>>generates 32-bit ints by default.  But the Alpha seems to do fine on 32-bit
>>>>ints.  And you can make a 64-bit int easily enough.
>>>>
>>>>So, I don't see what changing the OS and compiler to use 64-bit ints by default
>>>>will accomplish, in a chess programming sense.
>>>>
>>>>bruce
>>>
>>>Not really in a chess sprogramming sense, but a 64 bit address space would be
>>>nice for a lot of applications. I work at a small-to-medium size business and
>>>some of our stuff thrashes our 384MB server. An upgrade to almost 1GB is planned
>>>for soon. In a few years i expect us to need more than 4GB. Alpha/Linux would be
>>>a serious option if we wanted this right now. I suppose places with more Windows
>>>NT expertise would prefer NT, if and when it goes 64 bit.
>>>
>>>For chess, is suppose there might be some advantage in really huge transposition
>>>tables, or having the 5 piece EGTBs in ram instead of disc :-)
>>
>>
>>Xeon processors already support a 36 gigabyte address space for memory.  That
>>will be impossible to 'fill' for several years... as the best machines have 16
>>DIMM slots in them.  and we don't have 1 gig DIMMS yet...
>
>Yes, but those 36Gb is not the normal flat address space. You have to write the
>application in a special way to use it (as you should in the old DOS days to use
>EMS). Otherwise, you are still limited by 4Gb address space. I doubt there will
>be a lot of such applications - maybe some DBMS, if any.
>
>OS will be able to utilize that memory, of course - either for a lot of
>concurrent processes (each uses 4Gb max), or for a file caching.
>
>BTW, what is the maximum file size on Linux/Alpha?
>
>Eugene


The data structures are all "long".  So it is possible that the size of a
file is 2^64-1, but I don't have an alpha handy to try this on...  Wouldn't
surprise me if something broke however, as the 1-2-3 level indirect pointers
would suspect to have glitches for block numbers that big...  But it would
definitely be fun to find out. :)

Bob



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