Subject: Re: /dev on tmpfs problem
To: matthew green <>
From: Steven M. Bellovin <>
List: tech-kern
Date: 11/13/2005 21:59:49
In message <>, matthew green writes:
>   >    IMO removing tmpfs auto-sizing feature is a way to go.
>   >    ie. mandate -s option of mount_tmpfs and trust it.
>   > 
>   > 
>   > i want tmpfs to resize based on how much ram i have, or swap, or
>   > some cmobo, by default.  having to change static configuration
>   > parameters when i simply add memory is a concept that should be
>   > dead in this millennium...
>   i don't think that the appropriate size of the filesystem is
>   directly related to the total amount of memory on the system.
>   it's rather related to the purpose of the filesystem.
>   at least, it can't be mechanically calculated from the amount of memory.
>i'd hope that one day tmpfs on /tmp is the default config for
>a freshly installed netbsd system.  i don't think that it should
>require an explicit size and should just vary itself based on 
>the amount of ram/swap/something.
>i'm not saying i think it should use ALL ram/swap, but it seems
>the wrong thing to do to force size to be explicitly chosen.
Given the amount of (justifiable!) complaining we already see about how 
hard it is to get VM tuning correct, I don't think this is a good path 
to follow -- it adds one more element of unpredictability to system 
behavior.  At most, I think that sysinst could look at RAM and swap 
size and suggest that as the default -s option for /tmp.

		--Steven M. Bellovin,