XIPTECH CompactFS

Product

Service

CompactFS is not a File System, it's a compact driving layer. By inserting this layer into file system and block device driver, we can let the original file system be a "compact fs". Using CompactFS will slow down the system, the lost of performance will be 5 to 10 percent. But this is worth to embeded systems, which have not large flash rom.

Here is the compare of CompactFS and JFFS2
	compact fs	jffs2	comment
Compact ratio	same		they all use glib compact arithmetic
Performance	compact fs is better than jffs2		jffs2 compact the data whenever writes file,compact fs only do it when flush system disk cache into
Mount speed	quick	slow
Suitable for flash?	yes	yes	blocks of flash rom needs to be used averagely
Error recover	do by fschk	on mount time	this is the reason why jffs2 mount slowly
Portability	good	worse
check compact ratio of a file?	can
compact a file	can	cannot

Here is the typical compact ratio
catalogue	original size	zipped size	ratio
text	22M	5M	22.7%
24bit bmp	480K	195K	40.6%
exe	1M	0.3M	33%

Here is the result testing under Linux CPU 55MHz MIPS Samsung NAND Flash.

# iozone IOZONE:
Performance Test of Sequential File I/O -- V2.01 (10/21/94) By Bill Norcott
Operating System: POSIX 1003.1-1990
Usage: iozone [megabytes] [record_length_in_bytes] [[path]filename]
iozone auto[=filename]
iozone raw[=filename]
iozone cdrom[=filename]
iozone help
Send comments to: b_norcott@xway.com
IOZONE writes a 1 Megabyte sequential file consisting of 2048 records which are each 512 bytes in length. It then reads the file. It prints the bytes-per-second rate at which the computer can read and write files.
Writing the 1 Megabyte file, 'iozone.tmp'...1.670000 seconds
Reading the file...0.550000 seconds
IOZONE performance measurements:
627889 bytes/second for writing the file
1906501 bytes/second for reading the file

# bonnie
File './Bonnie.28', size: 1048576
Writing with putc()...done
Rewriting...done
Writing intelligently...done
Reading with getc()...done
Reading intelligently...done
Seeker 1...Seeker 3...Seeker 2...start 'em...
done...
done...
done...
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
1 188 48.5 431 35.8 290 28.4 414 100.0 6077 100.9 326.7 589
#