udev and kernel page size
I am using udev on my Alphastation 500/500 with nobse's kernel 2.6.10.
Looking into df -h shows:
none 5,0M 5,0M 0 100% /dev
and udev does not work anymore. The interesting thing is: if you create a
file in /dev and echo something in it - no error occurs. After that the
file is empty (bug in tmpfs?)
Looking through /dev/.udevdb which uses the whole space according to "du",
I see about 650 files with each about 20 to 40 bytes. On an Atlon box I
have the same .udevdb using a lot of fewer memory (about 1/8).
This is caused by the kernel page size on alpha machines which is 8192
Bytes, on athlon I think it is 1024 Bytes (correct? /proc/cpuinfo does not
show this). Each 20 Byte file so uses a page of 8192 Bytes *RAM* - not good.
I raised the maximum size in /etc/udev/udev.conf to 8 MB. Now df-h shows:
none 8,0M 5,3M 2,8M 66% /dev
udev now works but about 4.5 MB of RAM are wasted in comparison to x86
There are 3 solutions:
* raise the default maximum size of /dev in the udev.conf to a higher level
(this eats up no ram if for example limit ist very much higher but safe)
for alpha machines and other high-pagesize-processors - 4.5 MB of RAM wasted
* move udevdb elsewhere - speed issues
* rewrite udev to save the udevdb in a large file (best solution) - but
this is not Debian's issue.
Should we write a bug report to debian or udev people?
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