whatsnew-jan28,1998

Linux磁盘测试的源代码,测试磁盘的读写性能

January 28, 1998 Robin Miller

	The following changes have been made to 'dt' Version 10.12:

     o	Add dtaio_close() function, to wait for queued I/O's when we're
	aborting, to avoid kernel I/O AIO rundown problem, which panic's
	the system if we close the CAM disk driver device descriptor,
	prior to AIO's completing (fixed in steelos by Anton Verhulst).
	[ Refernce QAR Number 57040 for more information. ]

	NOTE:  This problem is very prevalent when doing "cable pulls"
		or otherwise forcing CAM disk I/O's into error recovery
		and then aborting running 'dt's.  This I/O waiting only
		occurs once, as a 2nd signal (i.e. "kill" or <Ctrl/C>
		simply exits the program.  Beware of "kill -9" :-)

     o	Don't initialize data buffer being written for "disable=compare"
	which yields better performance.  Also correct a problem referencing
	memory map (mmap) data due to compiler optimization (reference_data()
	use static volatile). [ Changes requested by Marcus Barrow, thanks! ]

	The latest version of 'dt' is available on our production machines
in the following account or from my web page, shown below:

		Location: wasted:~rmiller/dt.d/{dt-ptos,dt-dlm,dt-V3.2}
				or via
		URL: http://www.zk3.dec.com/~rmiller/dt.html

	NOTE: DLM version of 'dt' hasn't been recompiled yet!

Cheers,
Robin
================================================================================

im2fast% dt if=/dev/rrz0c iotype=random disable=compare runtime=3m enable=debug aios=250
dt: Attempting to open input file '/dev/rrz0c', mode = 00...
dt: Input file '/dev/rrz0c' successfully opened, fd = 9
dt: Data limit set to 1050040320 bytes, 2050860 blocks...
dt: Allocated buffer at address 0x14002e000 of 516 bytes, using offset 0
dt: Allocated buffer at address 0x140030000 of 516 bytes, using offset 0
dt: Allocated buffer at address 0x140034000 of 516 bytes, using offset 0
				.
				.
				.
	    [ <Ctrl/C> entered here to abort test... ]

Total Statistics:
      Input device/file name: /dev/rrz0c (Device: RZ26B, type=disk)
           Data pattern read: 0x39c39c39 (data compare disabled)
     Total records processed: 1080 @ 512 bytes/record (0.500 Kbytes)
     Total bytes transferred: 552960 (540.000 Kbytes, 0.527 Mbytes)
      Average transfer rates: 35829 bytes/sec, 34.989 Kbytes/sec
     Number I/O's per second: 69.978
      Total passes completed: 0
       Total errors detected: 0/1
          Total elapsed time: 00m15.43s
           Total system time: 00m00.08s
             Total user time: 00m00.01s
               Starting time: Wed Jan 28 10:17:32 1998
                 Ending time: Wed Jan 28 10:17:48 1998

dt: All requests completed before cancel...
dt: Closing file '/dev/rrz0c', fd = 9...
im2fast%