It is possible for multiple process to sleep concurrently waiting
for a buffer. When the buffer shortage is a shortage of space but
not a shortage of buffer headers, the processes took turns creating
empty buffers and waking each other to advertise the brelse() of
the empties; progress was never made because tsleep() always found
another high-priority process to run and everything was done at
splbio(), so vfs_update never had a chance to flush delayed writes,
not to mention that i/o never had a chance to complete.
The problem seems to be rare in practice, but it can easily be
reproduced by misusing block devices, at least for sufficently slow
devices on machines with a sufficiently small buffer cache. E.g.,
`tar cvf /dev/fd0 /kernel' on an 8MB system with no disk in fd0
causes the problem quickly; the same command with a disk in fd0
causes the problem not quite as quickly; and people have reported
problems newfs'ing file systems on block devices.
Block devices only cause this problem indirectly. They are pessimized
for time and space, and the space pessimization causes the shortage
(it manifests as internal fragmentation in buffer_map).
This should be fixed in 2.2.
1) fix k1-k4 to match XF3.3
2) fix kb,kD to match keyboard
3) merge xterm-color in: default description must match best current practice
and color card is most common variant for X now. Add xterm-mono entry for
mono cards.
Submitted by: Forgotten
Passed on by: Terry Dwyer 61 8 9491 5161 <tdwyer@io.telstra.com.au>
Also remove extraneous setuid(0) - it's only undone by
the subsequent call to SelectSystem().
should work with no driver changes, though not all features are currently
used.
Remove code that was conditional on NEW_SCSICONF not being defined. This
was temporary code, that at a time got excluded correctly, until the new
scsiconf became the default, and NEW_SCSICONF was no longer specified.
Add support for quirks defined in scsiconf.c. For now only the HP3724/5
needs an entry, since that drive can't be used with tags.
so don't enforce the MTU as an MRU. Allow bidirectional ppp MTU
negotiation, by checking against a differnt figure for MRU.
Make it large enough for ATM frames at least.
Submitted by: archie@whistle.com (archie cobbs)
o Allow "set var" with no args to blank var (don't req "").
o Zero VarTerm ASAP if not in interactive mode.
o Never print anything to stdout in -direct mode.
o Count redial when failing to open modem.
o Increase device size to 40 characters (for host:port).
o Remove missed "if (fd == 0) fd = 1;".
o Don't give up on incoming non-terminal connections.
