the wrong branch :-(]
Eliminate incorrect double negative logic Bruce has been gripping
about for a year now. Change = no_way to = true.
Submitted by: bde (sort of, patch by me :-))
proc or any VM system structure will have to be rebuilt!!!
Much needed overhaul of the VM system. Included in this first round of
changes:
1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
haspage, and sync operations are supported. The haspage interface now
provides information about clusterability. All pager routines now take
struct vm_object's instead of "pagers".
2) Improved data structures. In the previous paradigm, there is constant
confusion caused by pagers being both a data structure ("allocate a
pager") and a collection of routines. The idea of a pager structure has
escentially been eliminated. Objects now have types, and this type is
used to index the appropriate pager. In most cases, items in the pager
structure were duplicated in the object data structure and thus were
unnecessary. In the few cases that remained, a un_pager structure union
was created in the object to contain these items.
3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
be removed. For instance, vm_object_enter(), vm_object_lookup(),
vm_object_remove(), and the associated object hash list were some of the
things that were removed.
4) simple_lock's removed. Discussion with several people reveals that the
SMP locking primitives used in the VM system aren't likely the mechanism
that we'll be adopting. Even if it were, the locking that was in the code
was very inadequate and would have to be mostly re-done anyway. The
locking in a uni-processor kernel was a no-op but went a long way toward
making the code difficult to read and debug.
5) Places that attempted to kludge-up the fact that we don't have kernel
thread support have been fixed to reflect the reality that we are really
dealing with processes, not threads. The VM system didn't have complete
thread support, so the comments and mis-named routines were just wrong.
We now use tsleep and wakeup directly in the lock routines, for instance.
6) Where appropriate, the pagers have been improved, especially in the
pager_alloc routines. Most of the pager_allocs have been rewritten and
are now faster and easier to maintain.
7) The pagedaemon pageout clustering algorithm has been rewritten and
now tries harder to output an even number of pages before and after
the requested page. This is sort of the reverse of the ideal pagein
algorithm and should provide better overall performance.
8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
have been removed. Some other unnecessary casts have also been removed.
9) Some almost useless debugging code removed.
10) Terminology of shadow objects vs. backing objects straightened out.
The fact that the vm_object data structure escentially had this
backwards really confused things. The use of "shadow" and "backing
object" throughout the code is now internally consistent and correct
in the Mach terminology.
11) Several minor bug fixes, including one in the vm daemon that caused
0 RSS objects to not get purged as intended.
12) A "default pager" has now been created which cleans up the transition
of objects to the "swap" type. The previous checks throughout the code
for swp->pg_data != NULL were really ugly. This change also provides
the rudiments for future backing of "anonymous" memory by something
other than the swap pager (via the vnode pager, for example), and it
allows the decision about which of these pagers to use to be made
dynamically (although will need some additional decision code to do
this, of course).
13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
object" code has been removed. MAP_COPY was undocumented and non-
standard. It was furthermore broken in several ways which caused its
behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
continue to work correctly, but via the slightly different semantics
of MAP_PRIVATE.
14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
threads design can be worked around in other ways. Both #12 and #13
were done to simplify the code and improve readability and maintain-
ability. (As were most all of these changes)
TODO:
1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
this will reduce the vnode pager to a mere fraction of its current size.
2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
information provided by the new haspage pager interface. This will
substantially reduce the overhead by eliminating a large number of
VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
improved to provide both a "behind" and "ahead" indication of
contiguousness.
3) Implement the extended features of pager_haspage in swap_pager_haspage().
It currently just says 0 pages ahead/behind.
4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
via a much more general mechanism that could also be used for disk
striping of regular filesystems.
5) Do something to improve the architecture of vm_object_collapse(). The
fact that it makes calls into the swap pager and knows too much about
how the swap pager operates really bothers me. It also doesn't allow
for collapsing of non-swap pager objects ("unnamed" objects backed by
other pagers).
to su to root by authenticating as themselves (using a password or S/Key)
rather than by using the root password. This is useful in contexts like
ours, where a large group of people need root access to a set of machines.
(However, the security implications are such that this should not be
enabled by default.)
The code is conditionalized on WHEELSU.
isn't used in systat or in the kernel (it was replaced by a sysctl()
call involving VM_METER) and will go away when I clean up bogus
common variables in the kernel.
- There are two cases where the server can potentially block for a long
time while servicing a request: when handling a yp_all() request, which
could take a while to complete if the map being transfered is large
(e.g. 'ypcat passwd' where passwd.byname has 10,000 entries in it),
and while doing DNS lookups when in SunOS compat mode (with the -dns
flag), since some DNS lookups can take a long time to complete. While
ypserv is blocked, other clients making requests to the server will
also block. To fix this, we fork() ypall and DNS lookups into subprocesses
and let the parent ypserv process go on servicing other incoming
requests.
We place a cap on the number of simultaneous processes that ypserv can
fork (set at 20 for now) and go back to 'linear mode' if it hits the
limit (which just means it won't fork() anymore until the number of
simultaneous processes drops under 20 again). The cap does not apply
to fork()s done as a result of ypxfr calls, since we want to do our
best to insure that map transfers from master servers succeed.
To make this work, we need our own special copy of svc_run() so that
we can properly terminate child processes once the RPC dispatch
functions have run.
(I have no idea what SunOS does in this situation. The only other
possibility I can think of is async socket I/O, but that seems
like a headache and a half to implement.)
- Do the politically correct thing and use sigaction() instead of
signal() to install the SIGCHLD handler and to ignore SIGPIPEs.
- Doing a yp_all() is sometimes slow due to the way read_database() is
implemented. This is turn is due to a certain deficiency in the DB
hash method: the R_CURSOR flag doesn't work, which means that when
handed a key and asked to return the key/data pair for the _next_
key in the map, we have to reset the DB pointer to the start of the
database, step through until we find the requested key, step one
space ahead to the _next_ key, and then use that. (The original ypserv
code used GDBM has a function called gdbm_nextkey() that does
this for you.) This can get really slow for large maps. However,
when doing a ypall, it seems that all database access are sequential,
so we can forgo the first step (the 'search the database until we find
the key') since the database should remain open and the cursor
should be positioned at the right place until the yp_all() call
finishes. We can't make this assumption for arbitrary yp_first()s
and yp_next()s however (since we may have requests from several clients
for different maps all arriving at different times) so those we have
to handle the old way.
(This would be much easier if R_CURSOR really worked. Maybe I should
be using something other than the hash method.)
(on an i486, 10 cycles (+ cache misses) instead of 15). The
change should be a no-op if the compiler is any good. The best
possible i*86 code for the same algorithm is only 1 more cycle
faster on i486's so I don't want to bother implementing an
assembler version.
scanc() is a bottleneck for OPOST processing. It is naturally
about 4 times as slow as bcopy() on 32-bit systems.
were two races:
- q_to_b() might unexpectedly return 0 (e.g, after a keyboard signal
flushes the output queue and isn't echoed). ansi_put() interprets
0 bytes as 4GB...
- more output (e.g. for echoes) might arrive afer q_to_b() returns 0.
Then scstart() returns presumably and the new output might not be
handled for a long time.
Remove unused function scxint().
Fix prototypes (foo() isn't a prototype).
syscons' output is now only about 4-5 times slower than I want.
It loses a factor of 2 for scrolling output by unnecessarily copying
the screen buffer, a factor of 4/3 for dumb OPOST processing, and
a factor of 3/2 for clist processing.
fclosed twice and this didn't seem to cause any problems, but when
/var/crash was on an an unwritable nfs-mounted partition, fclose(NULL)
caused a core dump.
Adds support for non-Sound Blaster host adapters, including those
distributed by Reveal, Lasermate, IBM, Media Vision, Crystal and others.
The driver automatically senses the correct adapter type and you can
have both in the system at the same time.
(This change should eliminate a few complaints.)
Corrected bit-masking problem that prevented use on SB Vibra-16 boards.
Declared some internal data and functions static that should have been
that way all along.
Documentation changes reflect the new hardware support and change the
appearance version to 2.0.5 (was 2.1). Nice and tidy. :-)
Beta testers have verified functionality on SB16, Vibra-16, Media Vision
and Reveal adapters. -Wall still shows no warnings.
Frank Durda IV
uhclem%nemesis@fw.ast.com
Submitted by: Frank Durda IV <uhclem%nemesis@fw.ast.com>
to do something else than "install". For example,
make IS_DEPENDED_TARGET=fetch fetch
will fetch the required distfiles including those of the dependencies
without actually building and installing dependencies.
Also document ECHO_MSG.
Requested by: paul
Reviewed by: paul, jhs and others
or ssthresh that we were able to use
tcp_var.h - declare tcpstat entries for above; declare tcp_{send,recv}space
in_rmx.c - fill in the MTU and pipe sizes with the defaults TCP would have
used anyway in the absence of values here
>Synopsis: Booting w/scsi tape in drive causes first use to fail
Booting with a tape in a SCSI tape drive will cause the first
use of the tape to fail with the following message:
st0: bad request, must be between 0 and 0.
Submitted by: mpp@legarto.minn.net (Mike Pritchard)
that call vnode_pager_alloc() so that a failure return can be dealt with.
This fixes a panic seen on NFS clients when a file being opened is deleted
on the server before the open completes.
syscall to allow applications linked against their libc's uname() to
work. Netscape 1.1N being a prime example, which prints:
"uname() failed. cant tell what system we're running on".
This change is a little ugly, but that's mainly because of the "interesting"
semantics of the BSDI extension.
Since ogetkerninfo() is only enabled by COMPAT_43, Netscape will only
be affected on kernels with that option (eg: "GENERIC")
Reviewed by: davidg
