Messages in this thread |  | | | Date | Thu, 6 Aug 1998 02:33:02 +0200 (CEST) | | From | Andrea Arcangeli <> | | Subject | Re: DEVFSv50 and /dev/fb? (or /dev/fb/? ???) |
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On Thu, 6 Aug 1998, Richard Gooch wrote:
>> So with devfs after you have connected a PCMCIA card, in some msec >> automagically the right devfs device is added to /dev/ or /devfs/? > >Yup.
Nice ;-).
>> >Erm, if you just move all block devices into their own subdirectory, >> >and assuming the bulk of /dev bloat is due to block devices >> >(reasonable, when you consider the zillions of possible SCSI discs >> >when we break the 16 disc limit), then searching through /dev/block is >> >nearly as long as searching /dev with everything in it. >> >> With the current inode scheme nobody force you to put all blocks device in >> the same directory. I will use /tmp/myhd to be fast. > >That looks like a hack to me.
Isn' t devfs an hack?
>> And the device-file lookup in the case of block devices is done only at >> mount time (I hope to be right here ;-) so it' s really not importatnt and > >Actually, it's done at open(2) time. That's done by mount(8), fdisk(8) >and so on. Also if you want to list the directory, it takes more time.
andrea@dragon:/tmp/linux$ ls -lu /sbin/fdisk -rwxr-xr-x 1 root root 38820 Jul 18 00:57 /sbin/fdisk
18 Jun was the date of my last backup.
>It gets worse if you do "ls -lF" or something, which causes a stat(2) >of each inode.
I don' t look at /dev/ from ages.
>Mounting isn't the only time you need to access those inodes. Also, >think about those with a small CPU: extra (noticable!) delay at boot >time is unwelcome.
We are talking of msec on a 486 with a populated /dev/ I guess.
BTW, with the exciting idea of using btrees for storing directory entries, the inode lookup will be a lot _faster_.
Richard I had to specify that with my arguments I don' t care at all of people other than me. I don' t know how much useful can be devfs for distributors or for people that use Linux only to repartition HDs. I can tell that devfs is useful for me _only_ for the major/minor numbers thing. If in the near future there will be a cleaner way to handle >256 minor numbers devfs will be only overhead _for_me_.
Andrea[s] Arcangeli
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