Make part of John Birrell's KSE patch permanent..
Specifically, remove:
Any reference of the ksegrp structure. This feature was
never fully utilised and made things overly complicated.
All code in the scheduler that tried to make threaded programs
fair to unthreaded programs. Libpthread processes will already
do this to some extent and libthr processes already disable it.
Also:
Since this makes such a big change to the scheduler(s), take the opportunity
to rename some structures and elements that had to be moved anyhow.
This makes the code a lot more readable.
The ULE scheduler compiles again but I have no idea if it works.
The 4bsd scheduler still reqires a little cleaning and some functions that now do
ALMOST nothing will go away, but I thought I'd do that as a separate commit.
Tested by David Xu, and Dan Eischen using libthr and libpthread.
longjmp to the default context. As result, "alltrace" command may
be prematurely terminated (without error message). This is happens,
for instance, when system is low on memory and referenced page in
kernel-mode thread stack is swapped out.
Protect "alltrace" against termination on trap by setting temporary
kdb_jmpbuf context.
Submitted by: Peter Holm
since they just duplicated the MI `reset' command. Instead of removing
them, make `reboot' an MI alias for `reboot' since this gives a better
way of killing the `r' alias for `reset'. Remove the `registers' command
that was used to kill the alias.
Turn the powerpc and sparc64 MD `halt' command into an MI command.
A copy of sparc64/db_interface.c grew in sun4v just after I found the
extra reboot commands. It has not been changed, and is now not
identical. Duplicated commands come out duplicated in ddb's online
help, but cause large problems when used (e.g., on i386's with 2 halt's
and an hwatch, typing h doesn' give the expected message about an
ambiguous command, but hangs like the halt command or a looping parseri
would).
suppression is only needed at ends of lines, but rev.1.32 forced it
off precisely there.
The --More-- prompt is now cleared by explicitly forcing out the
whitespace in "\r \r". It might be better to use the line
editor's clearing functions, but these are currently static and not
much different.
- `b' is now an official alias for `break'. It used to be an unofficial
alias, but this was broken by adding the `bt' alias for `trace'.
- `t' is now an official alias for `trace'. It used to be an unofficial
alias, but this was broken by adding the `thread' command.
- `registers' is now an alias for `show registers'. This is a hack to
break the unofficial `r' alias for `reset'. `r' really means
`registers' in some debuggers, so I sometimes type it accidentally and
am annoyed when it resets the system. A short command shouldn't have
such a large effect. Now at least `res' must be typed to disambiguate
`reset'.
output width of 79, only 6 columns of width 12 each fit, but 7 columns
were printed.
The fix is to pass the width of the next output to db_end_line() and
not assume there that this width is always 1.
Related unfixed bugs:
- 1 character is wasted for a space after the last column
- suppression of trailing spaces used to limit the misformatting, but
seems to have been lost
- in db_examine(), the width of the next output is not know and is
still assumed to be 1.
- Right justify 'pid' label.
- Move the uid column to the right 2 columns so that the 3 process id
columns (pid, ppid, pgrp) are grouped together.
- Expand the uid column to 5 chars.
- Don't indent the tid for multithreaded processes.
Requested by: bde (1, 2, 4)
install custom pager functions didn't actually happen in practice (they
all just used the simple pager and passed in a local quit pointer). So,
just hardcode the simple pager as the only pager and make it set a global
db_pager_quit flag that db commands can check when the user hits 'q' (or a
suitable variant) at the pager prompt. Also, now that it's easy to do so,
enable paging by default for all ddb commands. Any command that wishes to
honor the quit flag can do so by checking db_pager_quit. Note that the
pager can also be effectively disabled by setting $lines to 0.
Other fixes:
- 'show idt' on i386 and pc98 now actually checks the quit flag and
terminates early.
- 'show intr' now actually checks the quit flag and terminates early.
in parallel in several threads, one symbol lookup could
clear db_last_symtab when another one going to use it as
starting point for traversal.
Approved by: pjd (mentor)
MFC after: 1 month
now back to using fixed-size columns for output and each line of output
should fit in 80 columns on both 32-bit and 64-bit architectures. In
general the output is close to that of the userland ps(1) with the
exception that the 'wmesg' field is mostly similar to the "state" field
in top(1) in that it will show either a wmesg, a lock name (prefixed with
an *), "CPU xx" (for a running thread), or nothing if none of those three
conditions are true. It also respects td_name when listing threads in
a multithreaded process. There is a somewhat evilly-defined PTR64 macro
I use to make account for the change in the size of the 'wchan' column
in the formatted output (wchan is now the only pointer in the ps output
and is available so it can be passed to 'show sleepq', 'show turnstile',
or 'show lock').
- Add two new commands "show proc [process]" and "show thread [thread]"
that show details about the specified process or thread (specified
either by pid/tid or pointer), respectively. If an address it not
specified, it uses the current kdb thread.
take the addr value passed to a ddb command and attempt to use it to
lookup a struct thread * or struct proc *, respectively. Each function
first reparses the passed in value as if it was an ID entered in base 10.
For threads the ID is treated as a thread ID, for proceses the ID is
treated as a PID. If a thread or proc matching the ID is found, it is
returned. For db_lookup_thread(), if the check_pid argument is true and
it didn't find a thread with a matching thread ID, it will treat the ID as
a PID and look for a matching process. If it finds one it returns the
first thread in the process. If none of the ID lookups succeeded, then
the functions assume that the passed in address is a thread or proc
pointer, respectively. This allows one to use tids, pids, or structure
pointers interchangeably in ddb functions that want to lookup threads or
processes if desired.
table. Previously, the ddb code knew of each linker set of auxiliary
commands and which explicit command list they were tied to. These changes
add a simple command_table struct that contains both the static list of
commands and the pointers for any auxiliary linker set of additional
commands. This also makes it possible for other arbitrary command tables
to be defined in other parts of the kernel w/o having to edit ddb itself.
The DB_SET macro has also been trimmed down to just creating an entry in
a linker set. A new DB_FUNC macro does what the old DB_SET did which is
to not only add an entry to the linker set but also to include a function
prototype for the function being added. With these changes, it's now also
possible to create aliases for ddb functions using DB_SET() directly if
desired.
still works. Also, this is consistent with 'show pcpu' vs
'show allpcpu'. (And 'show allstacks' on OS X for that matter.)
- Add 'bt' as an alias for 'trace'. We already have a 'where' alias as
well, so this makes it easier for gdb-wired hands to work in ddb.
Ok'd by: rwatson (1)
Requested by: scottl (2)
MFC after: 1 day
- Make it so one can't call db_setup_paging() if it has already been called
before. traceall needs this, or else the db_setup_paging() call from
db_trace_thread() will reset the printed line number, and override its
argument.
This is not perfect for traceall, because even if one presses 'q' while in
the middle of printing a backtrace it will finish printing the backtrace
before exiting, as db_trace_thread() won't be notified it should stop, but
it is hard to do better without reworking the pager interface a lot more.
threads. This is quite useful if generating a debug log for post-mortem
by another developer, in which case the person at the console may not
know which threads are of interest. The output of this can be quite
long.
Discussed with: kris
MFC after: 3 days
pointer doesn't point to the first instruction of that function, but
rather to a descriptor. The descriptor has the address of the first
instruction, as well as the value of the global pointer. The symbol
table doesn't know anything about descriptors, so if you lookup the
name of a function you get the address of the first instruction. The
cast from the address, which is the result of the symbol lookup, to a
function pointer as is done in db_fncall is therefore invalid.
Abstract this detail behind the DB_CALL macro. By default DB_CALL is
defined as db_fncall_generic, which yields the old behaviour. On ia64
the macro is defined as db_fncall_ia64, in which a descriptor is
constructed to yield a valid function pointer.
While here, introduce DB_MAXARGS. DB_MAXARGS replaces the existing
(local) MAXARGS. The DB_MAXARGS macro can be defined by platforms to
create a convenient maximum. By default this will be the legacy 10.
On ia64 we define this macro to be 8, for 8 is the maximum number of
arguments that can be passed in registers. This avoids having to
implement spilling of arguments on the memory stack.
Approved by: re (dwhite)
was satisified for the rest of the kernel on the i386 build except for
these two files. Rather than adding a submarine include to pcb.h, I've
added proc.h here.
I forgot to include these with the original commit. Sorry folks.
When a series of traces is included in a bug report, this will make it
easier to tie the trace information back to ps or threads output,
each of which will show the pid or the tid, but usually not both.
control the number of lines per page rather than a constant. The variable
can be examined and changed in ddb as '$lines'. Setting the variable to
0 will effectively turn off paging.
- Change db_putchar() to force out pending whitespace before outputting
newlines and carriage returns so that one can rub out content on the
current line via '\r \r' type strings.
- Change the simple pager to rub out the --More-- prompt explicitly when
the routine exits.
- Add some aliases to the simple pager to make it more compatible with
more(1): 'e' and 'j' do a single line. 'd' does half a page, and
'f' does a full page.
MFC after: 1 month
Inspired by: kris
but with slightly cleaned up interfaces.
The KSE structure has become the same as the "per thread scheduler
private data" structure. In order to not make the diffs too great
one is #defined as the other at this time.
The KSE (or td_sched) structure is now allocated per thread and has no
allocation code of its own.
Concurrency for a KSEGRP is now kept track of via a simple pair of counters
rather than using KSE structures as tokens.
Since the KSE structure is different in each scheduler, kern_switch.c
is now included at the end of each scheduler. Nothing outside the
scheduler knows the contents of the KSE (aka td_sched) structure.
The fields in the ksegrp structure that are to do with the scheduler's
queueing mechanisms are now moved to the kg_sched structure.
(per ksegrp scheduler private data structure). In other words how the
scheduler queues and keeps track of threads is no-one's business except
the scheduler's. This should allow people to write experimental
schedulers with completely different internal structuring.
A scheduler call sched_set_concurrency(kg, N) has been added that
notifies teh scheduler that no more than N threads from that ksegrp
should be allowed to be on concurrently scheduled. This is also
used to enforce 'fainess' at this time so that a ksegrp with
10000 threads can not swamp a the run queue and force out a process
with 1 thread, since the current code will not set the concurrency above
NCPU, and both schedulers will not allow more than that many
onto the system run queue at a time. Each scheduler should eventualy develop
their own methods to do this now that they are effectively separated.
Rejig libthr's kernel interface to follow the same code paths as
linkse for scope system threads. This has slightly hurt libthr's performance
but I will work to recover as much of it as I can.
Thread exit code has been cleaned up greatly.
exit and exec code now transitions a process back to
'standard non-threaded mode' before taking the next step.
Reviewed by: scottl, peter
MFC after: 1 week
the thread ID and call db_trace_thread().
Since arm has all the logic in db_stack_trace_cmd(), rename the
new DB_COMMAND function to db_stack_trace to avoid conflicts on
arm.
While here, have db_stack_trace parse its own arguments so that
we can use a more natural radix for IDs. If the ID is not a thread
ID, or more precisely when no thread exists with the ID, try if
there's a process with that ID and return the first thread in it.
This makes it easier to print stack traces from the ps output.
requested by: rwatson@
tested on: amd64, i386, ia64
more generic, but that didn't actually happen. Since the feature to
switch backends (and historically this means from DDB to GDB) is
important, make sure people can do just that until such the generic
mechanism actually sees the light of day.
Suggested by: rwatson@
db_elf.c, db_kld.c: The new KDB backend supports both at the same time.
db_sysctl.c: The functionality has been moved to sys/kern/subr_kdb.c.
db_trap.c: The DDB entry point has been moved to sys/ddb/db_main.c.
Most of the changes are a direct result of adding thread awareness.
Typically, DDB_REGS is gone. All registers are taken from the
trapframe and backtraces use the PCB based contexts. DDB_REGS was
defined to be a trapframe on all platforms anyway.
Thread awareness introduces the following new commands:
thread X switch to thread X (where X is the TID),
show threads list all threads.
The backtrace code has been made more flexible so that one can
create backtraces for any thread by giving the thread ID as an
argument to trace.
With this change, ia64 has support for breakpoints.
sleep queue interface:
- Sleep queues attempt to merge some of the benefits of both sleep queues
and condition variables. Having sleep qeueus in a hash table avoids
having to allocate a queue head for each wait channel. Thus, struct cv
has shrunk down to just a single char * pointer now. However, the
hash table does not hold threads directly, but queue heads. This means
that once you have located a queue in the hash bucket, you no longer have
to walk the rest of the hash chain looking for threads. Instead, you have
a list of all the threads sleeping on that wait channel.
- Outside of the sleepq code and the sleep/cv code the kernel no longer
differentiates between cv's and sleep/wakeup. For example, calls to
abortsleep() and cv_abort() are replaced with a call to sleepq_abort().
Thus, the TDF_CVWAITQ flag is removed. Also, calls to unsleep() and
cv_waitq_remove() have been replaced with calls to sleepq_remove().
- The sched_sleep() function no longer accepts a priority argument as
sleep's no longer inherently bump the priority. Instead, this is soley
a propery of msleep() which explicitly calls sched_prio() before
blocking.
- The TDF_ONSLEEPQ flag has been dropped as it was never used. The
associated TDF_SET_ONSLEEPQ and TDF_CLR_ON_SLEEPQ macros have also been
dropped and replaced with a single explicit clearing of td_wchan.
TD_SET_ONSLEEPQ() would really have only made sense if it had taken
the wait channel and message as arguments anyway. Now that that only
happens in one place, a macro would be overkill.
