[comp.sys.transputer] I/O calls on the transputer.

vandana@MULTI.EE.USU.EDU (Vandana Rungta) (07/27/90)

	This I/O benchmark iocall.c was executed on different systems:

1) Sun 4/110
2) Sun 3/160
3) INMOS's T800 TRAM in a B411 module on INMOS's B014 transputer board using
   their parallel C compiler.

******************************************************************************

iocall.c

	Author:   Jan Stubbs, NCR, ..!sdcsvax!ncr-sd!stubbs

This benchmark tests speed of Unix system call interface and speed of cpu doing
common Unix io system calls.

Under normal circumstances, this benchmark will not actually cause any physical disk activity, but will just cause system buffer activity.


The source code for this benchmark:


#include <stdio.h>

char buf[512];
int fd, count, i, j;

main()
{
	fd = creat("/tmp/testfile",0777);
	close(fd);
	fd = open("/tmp/testfile",2);
	unlink("/tmp/testfile");
	for (i=0;i<=1000;i++) {
		lseek(fd,0,0);
		count = write(fd,buf,500);
		lseek(fd,0,0);
		for (j=0;j<=3;j++)
			count = read(fd,buf,100);
	}
	exit(0);
}

******************************************************************************
		
The results I got in terms of time taken on each system are:

1) Sun 4/110            0.067 sec
2) Sun 3/160            0.133 sec
3) T800 on B014        31.604 sec


Does anyone have any ideas as how to improve the performance on transputers?


Vandana Rungta         vandana@multi.ee.usu.edu

koontz%capvax.decnet@CAPSRV.JHUAPL.EDU ("CAPVAX::KOONTZ") (07/28/90)

Netters,

    Woops!  A correction.  In my previous message on iocall.c benchmarking, the 
numbers for my B008 results are backwards.  It should be:

    Trial 1: DMA disabled (polling)  4.231 sec
    Trial 2: DMA enabled             3.798 sec

Yes, enabling DMA makes it go a little faster (as one would expect).
Sorry, but it's Friday...nuf said.

Ken Koontz  koontz@capsrv.jhuapl.edu

paulf@braa.inmos.co.uk (Paul Fellows) (07/31/90)

> This I/O benchmark iocall.c was executed on different systems:
>
> 1) Sun 4/110
> 2) Sun 3/160
> 3) INMOS's T800 TRAM in a B411 module on INMOS's B014 transputer board using
>    their parallel C compiler.

> The results I got in terms of time taken on each system are:

> 1) Sun 4/110            0.067 sec
> 2) Sun 3/160            0.133 sec
> 3) T800 on B014        31.604 sec


> Does anyone have any ideas as how to improve the performance on transputers?


> Vandana Rungta         vandana@multi.ee.usu.edu

Use an IMS B422 SCSI Tram with a fast SCSI disk.

This will give you a sustained IO performance rate of 1.2 MBytes per second for
reads and 1.5 MBytes per second for writes for large data transfers.

(Reads are slower because the IMS B422 uses an IMS T222 which of course does
not have the improved links of the T425 and T80X).

Paul Fellows, INMOS Limited  | mail(uk): paulf@inmos.co.uk or ukc!inmos!paulf
Bristol,  England            |     (us): uunet!inmos.com!paulf
+44 454 616616 ex 547        | Internet: paulf@inmos.com