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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?

Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de - http://www.schindlers-software.de
eMails: uwe@thetaphi.de (private); info@schindlers-software.de (company)
Tel./Fax: +49 700 PCLATEIN (+49 700 72528346)

Schindlers Software - Home of Schindlers PC-LATEIN 3.10
DIE Software zum Lateinlernen!

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