Re: Linux ports (was: Linux 64 bit - Trillium)

From: Rogier Wolff (R.E.Wolff@BitWizard.nl)
Date: Mon Mar 06 2000 - 03:50:39 EST


Matti Aarnio wrote:
> On Sun, Mar 05, 2000 at 10:36:00AM -0500, willy@thepuffingroup.com wrote:
> > > - Crays (the non-vector models; I suspect that Linux doesn't
> > > would be very suitable on a vector-machine. But I could
> > > be wrong)
> >
> > i heard they don't have an MMU. ucLinux on a Cray, baby! I've heard
> > people talking about merging ucLinux into 2.5, but they're crazy people.
>
> On the contrary, those vector systems do have a MMU, but it isn't PAGED.
> And similarly, there is no demand PAGING, there is only SWAPPING.
> Everything of process out of memory, everything in to the memory.
> (This is one reason why those machines have humongous IO bandwidth..)

Aaargh!

Does that mean that I can't run:

        int *input_data;
        float *temp_data1;
        float *temp_data2;
        float *outputdata;

        main ()
        {
                input_data = malloc (HUGEVAL *sizeof (int));;
                temp_data1 = malloc (HUGEVAL *sizeof (float));;
                temp_data2 = malloc (HUGEVAL *sizeof (float));;
                outputdata = malloc (HUGEVAL *sizeof (float));;
                
                read_dataset (input_data, argv[1]);
                process_step_1 (input_data, temp_data1);
                process_step_2 (temp_data1, temp_data2);
                process_step_3 (temp_data2, outputdata);
                write_dataset (output_data, argv[2]);
        }

with say 1.5G datasets and just 4G of RAM?

4 * 1.5G is 6G, so it doesn't all fit into RAM at the same time, while
every processing step uses only 2 * 1.5G = 3G of RAM, which fits
easily.

                        Roger.

-- 
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
*       Common sense is the collection of                                *
******  prejudices acquired by age eighteen.   -- Albert Einstein ********

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