Filling RAM

DMcLeod dmcleod at
Tue Feb 5 12:33:19 EST 2008


I am seeing that as files are created, their approximate size is 
subtracted from the available memory. For example, assume I have /home  
mounted from /dev/mtdblock2, which is a jffs2 filesystem on NOR flash. 
The following procedure reproduces the problem consistently:

]# cat /proc/mounts
rootfs        /     rootfs  rw     0 0
/proc        /proc     proc     rw     0 0
sysfs        /sys     sysfs     rw     0 0
/dev/mtdblock2    /home     jffs2     rw,sync 0 0

]# cd /home
]# grep MemFree /proc/meminfo
22588 kB
]# dd if=/dev/zero of=1M.dat bs=1M count=1
]# grep MemFree /proc/meminfo
21522 kB
]# rm 1M.dat
]# grep MemFree /proc/meminfo
22576 kB

I'm fairly certain the file does get written to flash as it is 
noticeably slower than creating a file of the same size in ramfs. So it 
seems like the file is stored in RAM as well, how/why would this happen?

ps - XATTRS is off,  JFFS2_SUMMARY is off, JFFS2_VERBOSITY = 0,

Any help is greatly appreciated.

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