Messages in this thread | | | Date | Tue, 11 Aug 1998 20:15:47 -0400 (EDT) | From | "Andrew J. Anderson" <> | Subject | Re: DEVFSv50 and /dev/fb? (or /dev/fb/? ???) |
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On Wed, 12 Aug 1998, Chris Wedgwood wrote:
> Arguably, we could just drop backwards compatibility, as /etc/fstab > and getmntent(3) aren't defined by Unix98, but since most unix like > OSs have this in some shape of form I don't know how reasonable that is.
Take a look at a snippet from the AIX equivalent of /etc/fstab (/etc/filesystems):
/usr: dev = /dev/hd2 vfs = jfs log = /dev/hd8 mount = automatic check = false type = bootfs vol = /usr free = false
So there is precedence for a "different" format for filesystem information. (Even though I would call AIX more "like-unix" than "unix-like". ;-)
> I was about to as how often to devices actually get opened anyhow? I > would thing even on busy systems you could count the number of times > you access by device per hour on one hand. On most systems, only a > limited number of users and applications will use device inodes.
I know of a busy POP server that had to increase their connection rate above 40/sec, and their daemon syslog's every connection (via /dev/log), so there's at least one documented case. And let's not forget sendmail and ftp (in some setups), as well.
My other thought is a busy telnet server and pty's. Once you get up there in users, it may be quite often, perhaps as much as several times a minute. Not to mention utilties such as expect that use pty pairs, etc. Next would be modem/terminal servers, /dev/log, and perhaps the iBCS devices when running SCO and Xenix binaries (/dev/inet/tcp and such).
So if sorting though the /dev directory becomes unreasonable with many devices, then it truely could become an issue for some applications. I believe that I saw a time of up to 0.5 seconds wall clock posted earlier for an 'ls' on /dev (just tried it here -- 0.47 for 'ls', 3.94 for 'ls -l'). Consider a 0.5 second delay for a busy mail hub or pop server or ftp site per message syslog'ed. Store and forward, anyone? :)
> One last comment... devfs aside, if your are running off RO media, > how would you handle PCMCIA/USB/1384? (Or is this a silly question?)
Or things like updating /etc/mnttab, and other /etc files are what I wondered about.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Andrew Anderson http://amelia.db.erau.edu/~andrew/ if(!(family_tree=fork())){redneck=TRUE;}
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